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LABORATORY STUDIES 

IN 

MAMMALIAN ANATOMY 


WILDER 






















































I 












LABORATORY STUDIES 

IN 

MAMMALIAN ANATOMY 


BY 

INEZ WHIPPLE WILDER, A. M. 

PROFESSOR OF ZOOLOGY, SMITH COLLEGE, NORTHAMPTON, MASS. x 


SECOND REVISED EDITION 



PHILADELPHIA 

P, BLAKISTON’S SON & CO. 


1012 WALNUT STREET 


QL?igy 

.VAi 


Copyright, 1923, by P. Blakiston’s Son & Co. 



PRINTED IN U. S. A. 

BY THE MAPLE PRESS YORK PA 


HAY 14 *23 

©C1A704582 

'Wtf / 


PREFACE 


These outlines are not intended to supply the place either of 
a teacher oi a text-book. They are the result of several years’ 
experience in an attempt to work out an elementary laboratory 
course in anatomy which might serve as a scientific basis for 
an accompanying course of lectures in Human Anatomy and 
Physiology for undergraduates in Smith College. 

Because of the impracticability of the use of human material 
for this work, except in the case of the skeleton and of certain 
demonstration dissections, the attempt has been made to base the 
laboratory work upon the dissection of a variety of mammals, 
using freely, for comparison, as large a supply of accurate manikins 
and models illustrating the anatomy of the human body, as it is 
possible to obtain. As material for laboratory dissection, there¬ 
fore, the course here outlined makes use not only of the smaller 
mammals, but of such portions of the larger mammals as may be 
easily obtained in quantities sufficient for large classes through the 
agency of local markets or directly from abattoirs. 

For the smaller mammals, rabbits, white rats, and guinea 
pigs are used in most cases rather than cats, because of the 
great ease with which these rodents may be bred upon our own 
premises, and the consequent relief from the vexations of spirit 
arising from the morbid sentimentality, and unjust criticism, 
which are the invariable accompaniments of an attempt to 
obtain a sufficiently large number of cats to supply the needs of a 
laboratory. There is no reason, however, why cats or dogs 
should not be substituted for rodents for much of the labora¬ 
tory work, provided a sufficient number of specimens can be 
obtained, and for the most part the same outlines of work could 
be used with such slight modifications as the teacher would 
naturally suggest, or the intelligent student discover. 

Considerably more is included in this outline than can be done 
by the average undergraduate class in 150 hours of laboratory 


v 



VI 


PREFACE 


work, i.e., in a year of work with five hours of laboratory work 
weekly. This gives considerable flexibility to the course, since 
certain of the exercises may be omitted; or they may be abbre¬ 
viated or given in the form of demonstrations on the part of the 
teacher. Moreover, an outline which covers more ground than 
the class as a whole can cover, gives much opportunity for 
optional work on the part of those students who work more rapidly 
than the majority, or who have more time to devote to the 
subject. 

The course here outlined has been found to have not only a 
large practical value as a basis for intelligent living, but experi¬ 
ence has shown that it serves also as an excellent introductory 
college course in Zoology, (i) since its practical personal appeal 
is more generally felt by the beginning student, whose knowledge 
of the content of general Zoology is often slight and whose interest 
in and taste for the subject is most naturally developed by 
beginning at the point of personal interest; (2) since the course 
deals not merely with adult Human Anatomy and Physiology but 
involyes a study and comparison of many forms and stages of 
development, and thus gives a basis for understanding Com¬ 
parative Anatomy, Histology, Comparative Physiology, and 
Embryology; (3) since the course gives training in all the usual 
methods of laboratory study, such as the study of dissections, 
macroscopic and microscopic study and interpretation of sections 
in various planes, drawing conclusions from sets of measurements, 
and the performance of a few simple experiments involving the 
use of precise apparatus; and (4) since the course introduces the 
more usual forms of zoological technic, such as the preservation of 
material both for dissection and for microscopic study, the injec¬ 
tion of circulatory systems, the use of the microscope, and the 
preparation of microscope slides by teasing, by smears, and by 
sectioning. 

It is because of the nature of the course as a possible intro¬ 
duction to other work in Zoology that the BNA nomenclature, 
which has in general been followed in these outlines, has been 
departed from somewhat in the descriptive terms of orientation, 
DORSAL, VENTRAL, ANTERIOR, and POSTERIOR, which I have 
endeavored to use consistently in their comparative morpholog- 


PREFACE 


Vll 


ical sense. It will be noted, however, that no attempt is made 
here to distinguish technical terms and technical names by the 
use of a different type, since it is believed that a rational nomen¬ 
clature is nothing more than the most exact form of scientific 
language, and should be learned and used by the student as a 
language, rather than as a set of terms and names. Following 
this idea it is frequently found advisable to introduce the name 
of a structure or feature without information as to its exact loca¬ 
tion, when that name is such that the thoughtful consideration 
T)f its meaning on the part of the student will suffice to show its 
application; and it is my opinion that every effort should be made 
to induce the student to rely upon his own knowledge of Latin and 
Greek, as well as English, to help him in understanding and 
applying new terms. 

In many parts, the outline consists rather of a memorandum 
of the structures and relationships to be studied than of a set 
of definite directions for work, to be blindly and implicitly fol¬ 
lowed. This is the intentional expression of the feeling that, 
in the matter of dissection and study, the sooner the student learns 
to rely upon his own judgment and ingenuity the better, and that, 
under proper restrictions, individuality in the method of working 
should be developed even at the occasional expense of time and 
material. 

With regard to the method of recording the work done in the 
laboratory, it cannot be too strongly or too frequently empha¬ 
sized that such records, whether in the form of notes or draw¬ 
ings, are wholly for the student’s own personal use, and that 
with him lies the whole responsibility for their accuracy. They 
can have no value except as an expression of what the student 
has learned from his own study of laboratory material, and 
they should be as individual in their form as are the students 
themselves in their methods of study. Laboratory drawings, 
to express the true scientific attitude, should be in the nature of 
working drawings rather than of finished productions, and 
should be left in a sufficiently plastic form to admit of modifica¬ 
tions and additions, if at any time a more accurate or complete 
knowledge of the object is obtained. Thus, while drawings 
should be neatly executed and labeled, for a student to labor for 


Vlll 


PREFACE 


finished artistic effect, is not only inadvisable from the standpoint 
of time, but often leads to a sacrifice of scientific accuracy. 

In the preparation of the second edition of the book a consider¬ 
able rearrangement of the subject matter has been made because 
in the actual use of the book at Smith College the various instruc¬ 
tors have found that such a rearrangement constituted a more 
logical development of the subject as well as a more convenient 
method of administering the course. For these suggestions and 
many others which have been embodied in the revision I wish 
here to express my gratitude to the former and present members of 
the Department of Zoology of Smith College who have been my 
colleagues in the teaching of this course. 

Inez Whipple Wilder. 

Smith College, Northampton, Mass. 


TABLE OF CONTENTS 


Page 

I. General Anatomy of the Mammalian Body (10-14 Hours). . . 1 

A. The Bony Framework. 1 

B. General Relationships and Distribution of Muscles. 4 

C. The Cavities of the Body and Their Contents. 7 

D. The Plan of the Body as Shown in Transverse Sections and in a 

Median Sagittal Section.15 

II. Introductory Histological Study (10-12 Hours). 17 

A. Fresh Material.19 

B. Histological Sections (technic).22 

C. Permanent Mounts Showing Examples of Cells from Different 

Tissues.27 

D. Permanent Mounts Showing Mitosis.28 

E. Varieties of Epithelial Tissues.28 

III. Dissection of the Foot of the Pig for the Macroscopic Study of 

Skeletal Tissues (2-4 Hours).31 

IV. Histology of Skeletal Tissues (4-6 Hours).34 

A. Tensile or Connective Tissues.34 

B. Rigid Tissues.35 

V. The Human Skeleton (18-20 Hours).39 

A. The Vertebral Column, Ribs, and Sternum.39 

B. , The Skull.42 

C. The Appendicular Skeleton.45 

D. Suggested Supplementary Exercises.48 

VI. Histology of Muscle Tissue (2-4 Hours).50 

A. Smooth, or Unstriated, Involuntary Muscle.50 

B. Striated Voluntary Muscle.t . . . 50 

C. Striated Involuntary, or Heart, Muscle.51 

VII. Detailed Anatomy of Limb Muscles (8-20 Hours).52 

A. Anterior Limb Muscles.53 

B. Posterior Limb Muscles.55 

VIII. Histology of Nerve Tissues (6-8 Hours).59 

A. Nerve Cells.59 

B. Nerve Fibers.60 

C. Nerve Endings.62 


IX 

































X 


TABLE OE CONTENTS 


Page 

IX. The Spinal Cord and the Peripheral Nervous System (4-6 Hours) 66 

A. Gross Anatomy.66 

B. Structure of the Spinal Cord.68 

X. The Primitive Vertebrate Brain (2-6 Hours).71 

A. Dorsal Aspect of Dogfish Brain in situ .71 

B. Median Sagittal Section of Dogfish Brain, in situ . 11 

C. Comparative Study of Brains of Other Vertebrates. 72 

XI. The Mammalian Brain (10-12 Hours).73 

A. External Features.: . . 75 

B. Internal Structure.78 

XII. The Cranial Nerves and Special Sense Organs (10-12 Hours) 86 

A. The General Topography of the Head.86 

B. The Floor of the Cranial Cavity.86 

C. The Eye and the Nerve Distribution to It.87 

D. The Olfactory Organ and Its Accessories.91 

E. The Ear.92 

F. The Floor of the Mouth, and the Tongue.94 

XIII. The Thoracic Viscera (“Plucks”) of Some Large Mammal (4-8 

Hours).96 

A. The Trachea, Bronchi, and Lungs.97 

B. The Larynx . ..98 

C. The Heart and Large Blood Vessels.100 

D. Physiological Demonstrations.101 

XIV. The Blood Vessels (8-12 Hours).102 

A. Gross Anatomy of the Arteries and Veins.\ . 102 

B. The Capillaries.109 

C. Structure of the Walls of Blood Vessels.109 

D. Location of Superficial Blood Vessels in the Human Subject . .110 

E. Demonstrations of the Movements of the Blood.no 

XV. Blood (4-6 Hours).113 

A. Histology of Blood.113 

B. General Properties of Blood.116 

XVI. The Respiratory Process (6-8 Hours).119' 

A. Location of the Extent of the Lungs by Percussion.119 

B. Changes in the Dimensions of the Thorax and Abdomen of the 

Human Subject during Respiration.119 

C. Pneumograph Record of Respiratory Movements.121 

D. The Mechanics of Respiration.121 

E. Respiratory Sounds.X22 

F. Spirometer Measurements of the Volumes of Air Concerned in 

Respiration.122 

G. Demonstration of the Nature of Expired Air.123 

I 






































TABLE OF CONTENTS 


XI 


Page 

XVII. The Digestive System(6-8 Hours).*.124 

A. Gross Anatomy.124 

B. Physiological Demonstration. 126 

C. Histology.126 

XVIII. The Urogenital System (6-8 Hours) .131 

A. External Form and Relationships.131 

B. Structure.132 

XIX. The Development of Mammals (4-6 Hours) .137 

A. Demonstration of the Gravid Uterus.137 

B. Demonstration of Lactation. 137 

C. Developmental Stages.138 

D. Demonstration Preparations of Human Material.138 

Summary of Equipment and Material.139 

Index.151 


















MAMMALIAN ANATOMY 

I. GENERAL ANATOMY OF THE MAMMALIAN BODY 


A. THE BONY FRAMEWORK. 

Material. —Mounted skeletons of Man and other mammals, 
such as the orang, gibbon, cat, rabbit; disarticulated human 
skeletons; also manikins. 1 

Methods. —Identify the structures mentioned in the outline, 
by the aid of any good text or reference book on human or mam¬ 
malian anatomy. Note the differences in relationships involved 
in man’s assumption of an erect position. 

The aim of this general study of the skeleton should be (i) to 
become familiar with the bones and the groups of bones in their 
relation to each other and to the external form of the body, and 
(2) to be able to identify separate bones at sight to the extent 
of knowing the names of the larger and more distinctive ones, and 
the name of the group to which the smaller ones belong. Separate 
bones should always be identified and distinguished as right or left 
in the case of paired bones, referring them to the articulated 
skeleton and thus learning to think of them in their correct position 
in relation to the body as a whole. 

Terms of Orientation. —To orient any structure of the body is 
to place it in its correct relationship to the body as a whole, 
i.e., in the relation which it had when in place in the body. In the 
quadruped animal in the normal position, with the axis of the 
body horizontal, the surface or region of any part of the body 
which is directed upward is described as dorsal in position, while 
that which is directed downward is ventral; the surface or region 

1 In addition to the usual types of anatomical manikin, the manikin of B. Suzuki, 
especially adapted to the study and location of superficial features, will be found 
useful. This manikin, which represents a Japanese athlete with all external features 
slightly exaggerated, has a washable surface, neutral in color, and may thus be used 
with crayons of any color for demonstration purposes or for class drill in the location 
and identification of superficial parts. See Anatomischer Anzeiger , Vol. 37, Sept. 17, 
1910. 


1 


2 


MAMMALIAN ANATOMY 


which is directed forward is anterior, that directed backward is 
posterior; the surface or region which is directed toward the 
median vertical plane is medial, that directed away from this 
plane is lateral; in the free limbs, proximal applies to a region 
nearer to the trunk and distal to a region farther away from the 
trunk. These terms are also used to describe the relative location 
of different parts, one part being anterior to, dorsal to, or medial 
to, another. In the free limbs, the surface toward which the 
bending of the limb as a whole takes place (i.e., at the elbow or 
knee), is the flexor surface, while the opposite surface is the 
extensor surface. In the case of a body like the human body 
which has come to take an erect position, the terms of orientation 
may be applied as if the body were still in the horizontal position. 1 

i. Grouping of Parts. 

Record your study by a conventionalized diagram of the human 
skeleton on as large a scale as the size of the page of your note book 
affords 2 showing relationships and names of the groups of bones , 
and the numbers of the bones of each group , with the names of indi¬ 
vidual bones so far as given in the outline . In this case , as in all 
laboratory work, supplement the diagram freely with notes explaining 
points which the diagram does not show. 

(a) Axial Skeleton. 

Skull. —Cranial region, facial region. Compare man with 
other mammals as to the relationship of these to each 
other in relative size and location. 

Vertebral Column. —Note number of vertebrae in each 
group. 

Cervical vertebrae. 

Thoracic vertebrae (rib-bearing). 

Lumbar vertebrae. 

Sacrum (sacral vertebrae). 

Coccyx (caudal vertebrae). 

1 The BNA (Basle Anatomical Nomenclature) which is applied to the human 
body without reference to its comparison with other forms, uses posterior and 
anterior as synonymous with dorsal and ventral respectively, and substitutes 
superior and inferior for anterior and posterior respectively. 

2 A convenient size for laboratory note books for this course has been found to be 
about io X 14 inches. A good quality of unruled, smooth paper, of rather light 
weight, is recommended. 


GENERAL ANATOMY OF THE MAMMALIAN BODY 


3 


Ribs. —True, false, floating—note number of each and 

possibilities of variation. 

Sternum. —Note relation to the ribs. 

( b ) Appendicular Skeleton. 

Girdles. 

Pectoral.—Clavicles, scapulae. 

Pelvic.—Ossa coxae, each consisting of iliac region, ischial 
region, and pubic region. 

Appendages. 

Anterior (Arm).—Humerus, radius and ulna, carpus, 
metacarpus, phalanges. 

Posterior (Leg).—Femur, patella, tibia and fibula, tarsus, 
metatarsus, phalanges. 

2. Cavities Outlined by the Skeleton. 

In Head. —Cranial region of the neural cavity, auditory 
cavities, orbital cavities, nasal cavities, mouth cavity. 

In Trunk. —Spinal region of neural cavity, or spinal canal 
(continuation posteriorly of the cranial cavity); body cavity (or 
coelom), divisible into thoracic, abdominal, and pelvic regions. 

A 

3. Identification of Superficial Bony Parts upon the Living Body. 

Method.— By palpation locate upon your own body, or that of a 
fellow-student or a laboratory subject, those bony surfaces, ridges, 
and other protuberances which are superficial and thus readily felt 
through the skin. By comparison with an articulated human 
skeleton, and with anatomical manikins, discover the identity of 
each superficial region thus located, and from the following list, 
with the aid of anatomical atlases and reference books, learn the 
names of these superficial bony parts. Record the location of the 
superficial bony parts thus identified, upon outline drawings 1 of 
the human body, ventral, lateral and dorsal views, supplied by the 
laboratory . 

In Head.— Dome of cranium, from the occipital protuberance 
to the superciliary arches; mastoid processes, zygomatic arches, 

1 Outline drawings of the human body in ventral, lateral, and dorsal aspects may 
be readily traced from various art atlases by the individual students, or such a 
tracing may be manifolded by means of a mimeograph, hectograph, or other mani¬ 
folding apparatus. 



4 


MAMMALIAN ANATOMY 


malar surfaces, nasal bones, mental protuberance, angles of jaw; 
within the mouth, alveolar ridges, hard palate, coronoid processes 
of lower jaw. 

In Trunk. —Spinous processes of all the vertebrae, especially 
the 7th cervical (vertebra prominens), end of coccyx; anterior 
margin of the manubrium of the sternum (the jugular notch), 
posterior end of sternum (the xiphoid process), outline of costal 
cartilages from the 7th to the 10th (forming the superficial 
boundary between thorax and abdomen), outline of ribs (nipple 
between the 4th and 5th). 

In Pectoral Region and Arm. —Medial half of clavicle, acro¬ 
mion process of scapula, coracoid process of scapula, spine of 
scapula, vertebral border of scapula; larger tubercle of the humerus; 
lateral and medial epicondyles of the humerus; olecranon of ulna; 
ridge of shaft of ulna, styloid process of ulna; head of radius; 
distal fourth of shaft of radius; styloid process of radius; the 
pisiform bone, the distal ends of metacarpals; proximal and distal 
ends of the rows of phalanges. 

In Pelvic Region and Leg. —Crest of ilium, sciatic tuber, pubic 
arch, pubic symphysis, greater trochanter of femur, lateral and 
medial epicondyles of femur, patella, lateral and medial condyles 
of the tibia, tuberosity of tibia, crest and medial surface of tibia, 
medial malleolus, lateral malleolus; tuber of the calcaneus (heel), 
tuberosity of 5 th metatarsal, proximal and distal ends of rows of 
metatarsals and phalanges. 

B. GENERAL RELATIONSHIPS AND DISTRIBUTION OF 
MUSCLES. 

1. Demonstration of Muscle Relationships and Distribution in a 
Freshly Killed Mammal. 1 

Note the readiness with which superficial bony parts may be 
located through the skin by palpation. Note that in skinning 

1 The specimens used in this study of the general distribution of muscles (prefer¬ 
ably cats or rabbits) may be very conveniently preserved for the later detailed study 
of muscles by the method given on p. 52. If, on the other hand, the supply of 
material is insufficient to allow another set of fresh specimens for the study of the 
viscera, immediately following, the study of the general distribution of muscles * 
mhy be made first from manikins and casts, and the demonstration of the actual 
muscles can then be taken briefly when the freshly killed specimens for the study 
of the viscera are skinned. 


I 


GENERAL ANATOMY OF THE MAMMALIAN BODY 5 

and dissecting an animal, it is important to use well-sharpened 
scalpels, which should be kept in good condition by frequent 
sharpening during the dissection. During the process of dissec¬ 
tion the preparation must be kept from drying by frequent 
applications of water. During the removal of the skin note its 
thickness, and the thin layer of subcutaneous muscle or panniculus 
carnosus, with its lines and regions of deeper attachment. 
Observe, incidentally, the loose connective tissue, or areolar tissue, 
which holds all parts together and is particularly well seen in the 
subcutaneous region where it holds the skin loosely to the under¬ 
lying muscles. Note fibrous connective tissue membranes 
(aponeuroses and fasciae) covering certain muscle masses and 
serving for the attachment of some of the muscles. Numerous 
blood vessels, both veins and arteries, and many nerves, will be 
seen during the process of skinning. 

In the skinned specimen, compare the general proportions of 
the body with those of man, and note in the latter the modifica¬ 
tions of structure and proportions due to the erect attitude. 

Note that the musculature is so applied to the bony skeleton as 
to fill in its hollows and spaces, and leave in general only the more 
prominent bony processes and surfaces uncovered and hence super¬ 
ficial in location. (For names of these cf. A3, pp. 3 and 4.) 

Important muscle masses in different regions of the body, with 
names of those muscles which are superficially located and thus 
form prominent external contours of the body: 

Facial or Mimetic Muscles. —Note that these include the 
muscles of the external ears. 

Muscles of the Lower Jaw or Mandible. —Note particularly 
the temporalis and masseter muscles. 

Muscles of the Neck. —(The sternocleidomastoideus so 
prominent in man, is here represented by two inconspicuous 
muscles.) 

Muscles of the Shoulder and Chest. —Note particularly on the 
dorsal side the trapezius muscle and the latissimus dorsi; on the 
central side the pectoralis muscle; the boundaries of the axilla 
formed by the edges of the latissimus dorsi and the pectoralis 
(dorsal and ventral “tendons” of the axilla); the serratus anterior, 
appearing on the lateral thoracic wall in the space between the 


6 


MAMMALIAN ANATOMY 


pectoralis and the latissimus dorsi; the deltoid muscles covering 
the shoulder joint. 

Muscles of the Vertebral Column. —Note that it is only in the 
lumbar region that these are not covered by superficial muscles of 
other groups, and thus contribute to the external contours of the 
body. 

Intercostal Muscles. —Note that these muscles fill in the spaces 
between the successive ribs. 

Abdominal Muscles. —Note particularly the two rectus 
abdominis muscles, arranged longitudinally one upon each side 
of the midventrally located linea alba, which extends from the 
posterior end of the sternum to the symphysis pubis. The other 
abdominal muscles are disposed in three layers forming the 
lateral and latero-ventral walls of the cavity. 

Muscles of the Hip Region. —Note particularly the gluteus 
group and compare with man, in whom these muscles are so 
much more prominently developed to hold the legs in a straight 
line with the axis of the trunk. 

Flexors and Extensors of the Appendages.— Among these, 
note, in the anterior appendage, the biceps brachii and the triceps 
brachii, and the flexors and extensors of the carpus and fore foot 
(hand), with their respective tendons of insertion. In the pos¬ 
terior limb, note the extensor quadriceps femoris with its relation 
to the patella, and the flexors of the leg, forming at the knee joint 
the “outer and inner hamstrings;” the triceps surse (calf of the 
leg) and its tendon of Achilles, and the tibialis anterior and 
other extensors of the foot with their tendons of insertion. 
(The foot is habitually over extended, i.e., ‘‘flexed” in the 
wrong direction.) 

2. Identification of Superficial Muscles and Their Tendons upon 
the Living Human Body. 

Locate these by palpation with the muscles in question strongly 
contracted, and identify the muscles or muscle groups by referring 
to manikins, plaster casts showing muscle dissections, and atlases. 
Record the location of these muscles and tendons upon the outline 
drawings of the human body , noting their relationship to superficial 
skeletal features already recorded. 


GENERAL ANATOMY OF THE MAMMALIAN BODY 


7 


Temporalis. 

Masseter. 

Sternocleidomastoideus. 

Pectoralis group and ventral tendon of axilla. 

Trapezius. 

Serratus anterior. 

Latissimus dorsi and dorsal tendon of axilla. 

Deltoid. 

Biceps brachii, and its distal tendon. 

Triceps brachii. 

Flexor group of forearm, and flexor tendons of hand. 

Rectus abdominis. 

Gluteus group. 

Extensor quadriceps femoris (three superficial parts). 

Flexors of the leg; and their tendons of insertion (outer and inner “hamstrings”). 

Triceps surae and tendon of Achilles. 

Tibialis anterior and its tendon. 

Extensor tendons of the foot. 

C. THE CAVITIES OF THE BODY AND THEIR CON¬ 
TENTS, THE “ VISCERA.” 

Material. —Freshly killed specimens 1 (guinea pigs, rabbits, 
white rats or cats) Cf. with anatomical manikins of the human 
body. 2 

General Directions for Making Scientific Drawings.— All 

drawings should be oriented upon the page either with the anterior 
or the dorsal region of the part drawn uppermost; they should be 
made with careful attention to proportions and upon a sufficiently 
large scale to show clearly all of the structures studied. Use a 
well-sharpened hard (2H or 4H) pencil and draw with light 
trial lines which may be readily erased and changed as the work 
progresses; let every line which is finally left express a definite 
idea, and finish the drawing in pencil in clear-cut, definite, but 
never heavy outlines. Ink is inadvisable, and shading is in gen¬ 
eral ineffective and is for beginners, at least, a waste of time. 

J If rodents are used, they should not be fed for several hours previous to chloro¬ 
forming. The specimens used for this study of the viscera may be kept in good 
condition in a considerable volume of running cold water for 24 hours. Subsequently 
they may be preserved for further study in 5% formalin. Because of the irritating 
properties of formalin, however, material preserved in this way should be thoroughly 
washed out in running water for several hours before it is used. 

2 A very convenient model for comparison of this dissection with the human 
body is found to be that of the torso in the position for dissection, showing the 
thoracic and abdominal cavities and their contents. 


8 


MAMMALIAN ANATOMY 


The drawing as a whole should be accurately labeled and dated; 
and each part drawn should be labeled, if only tentatively, as 
soon as drawn, the temporary labels to be replaced by permanent 
ones in the final finishing of the drawing. Usually the most 
convenient method of permanent labeling is that of a set of neatly 
dotted, ruled, leading lines, which places the names of the parts at 
one side where they can be neatly written or printed. 

Order of Procedure in Dissecting. —Use strong forceps, scis¬ 
sors, and scalpels, the latter kept in a well sharpened condition 
during the dissection by frequent honing. Moisten the prepara¬ 
tion frequently, or in case a very small mammal is used, dissect 
under water. 

Remove the skin from the entire body, except from the feet and 
from the regions immediately surrounding the ears, eyes, nose, 
mouth, and the anal and urogenital orifices, 
i. The Coelomic Cavity, and Its Contents in situ. 

After a brief review of the superficial bony landmarks and 
general distribution of the muscles, open the abdominal cavity by 
a midventral incision from the posterior end of the sternum to the 
symphysis pubis, and make a transverse incision through the wall 
upon each side of the midline, sufficiently extensive to allow the 
ventral abdominal wall to be turned back in four flaps to expose 
the abdominal viscera in situ. 

Note that the anteribr boundary of the cavity is formed by 
the dome-shaped muscular partition, the diaphragm, which in 
the mammal subdivides the coelomic cavity transversely into the 
thoracic and the abdominal cavities. Posterior to the level of the 
pubic arch the coelom narrows and becomes the pelvic cavity. 

Note the smooth, moist serous membrane, known in the 
abdominal cavity as the peritoneum, the parietal portion of which 
lines the cavity throughout while the visceral portion, as will be 
seen more clearly later, invests and supports the contained organs. 

Identify the viscera so far as you are able without disarranging 
them. Most conspicuous of all is the voluminous coiled intestine. 
Anterior to this intestinal mass and partly hidden in the concavity 
of the diaphragm, are the stomach and the liver, the latter lying 
more on the right side, while the spleen which is located to the left 
of the stomach, may often be seen. 


GENERAL ANATOMY OF THE MAMMALIAN BODY 


9 


Posterior to the intestinal mass, at the level of the pubic arch, 
may be seen the urinary bladder, especially conspicuous if it 
happens to be distended with urine. If the animal is a male, 
certain of the accessory reproductive organs may be seen as slender 
pointed sacs upon either side in the posterior part of the cavity 
(especially in rodents). If the animal happens to be a female 
in advanced pregnancy, the much enlarged portions of the gravid 
uterus will be pushed up conspicuously into view . 1 

Make an outline drawing of the ventral view of the whole 
specimen , showing the abdominal cavity thus laid open and 
the contained organs in situ, and adding to the drawing as the work 
progresses. 

Cut the pectoralis muscles from their attachment to the ster- 
\ num upon each side and reflect them laterally, thus exposing the 
thoracic wall. 

Open the thoracic cavity by removing with the scissors a wide 
triangular portion of the latero-ventral wall upon each side of the 
midventral line leaving intact the whole line of costal cartilages 
which form the posterior border of the thoracic cavity, the ster¬ 
num, and the diaphragm, the full extent and relations of which 
may now be more clearly seen. Note attached to the inner surface 
of the sternum, the delicate mediastinum, which forms a median 
partition dividing the thoracic cavity into right and left pleural 
cavities. 

Within the space inclosed between the two layers of the medi¬ 
astinum, the heart will be seen enwrapped with its own serous 
membrane, the pericardium. The membrane which lines each 
pleural cavity is the parietal pleura, w T hich is continuous along the 
middorsal and midventral regions with the mediastinal pleura 
of its own side. The lung which lies in each pleural cavity is 
inclosed in the visceral pleura which is a reduplicature of the 
mediastinal pleura dorsal to the heart. 

1 In case there are embryos in the uterus, these should be examined while fresh, 
and their relation to the various extraembryonal parts (see p. 137) noted, after which 
each embryo should be carefully removed with the placenta still attached to it, and 
hardened in some good fixative such as that for which the formula is given on p. 22. 
It may subsequently be preserved to use for the study of the development of 
mammals (p. 137), or, if of suitable size, may be sectioned for the study of the 
general plan of the body (p. 15). 


IO MAMMALIAN ANATOMY 

Remove the sternum by severing its attachment to the dia¬ 
phragm and to the most anterior pair of ribs, and thus lay open 
ventrally the whole length and width of the thoracic cavity, the 
extent of which should be carefully noted. Study and identify 
the contained viscera in situ . 

Note the central position of the heart and observe the large 
blood vessels which lead into and from it. Note that the parietal 
pericardial membrane forms a loose sac about the heart. Care¬ 
fully lay this open and observe that the reduplicature which con¬ 
stitutes the visceral pericardial membrane is closely applied to 
the surface of the heart. Note the dark red appearance of the 
thin-walled anterior chambers of the heart, the auricles, due to 
their distension with blood, and the paler appearance of the thick- 
walled, muscular posterior chambers, the ventricles. In life the 
lungs, here seen in a collapsed condition, are distended with air 
and practically fill the pleural cavities. (Cf. specimen in which the 
lungs have been artificially inflated.) 

If the heart and lungs be gently drawn to the right side, the 
tubular oesophagus may be seen extending lengthwise through the 
dorsal mediastinal space. The air passages connecting with each 
lung unite dorsal to the heart to form the trachea. Since this is 
concealed in the thoracic region by the heart and large blood 
vessels as well as by the thymus gland, which in most mammals 
(but not in the guinea pig) is located in the mediastinal space 
anterior to the heart, it is advisable to first locate the trachea in 
the neck region. This may be done by carefully separating the 
glandular masses of the neck and then separating the two delicate 
ribbon-like muscles which extend lengthwise upon either side of 
the median line immediately over the trachea. The trachea will 
be readily recognized by the presence of cartilaginous rings in its 
walls. Dorsal to the trachea and in direct contact with it lies 
the oesophagus. The trachea and oesophagus may now be traced 
posteriorly to the narrow anterior orifice of the thoracic cavity 
through which they pass in company with the large blood vessels 
which supply the anterior region of the body. 

The trachea will be found to extend anteriorly the whole length 
of the neck. Its anterior end is differentiated to form the larynx. 
The oesophagus similarly extends the whole length of the neck. 


GENERAL ANATOMY OF THE MAMMALIAN BODY II 

Pry open the mouth and demonstrate, by probing, the con¬ 
nection of each of these passages with the pharyngeal cavity into 
which the mouth cavity leads posteriorly. The large jugular 
vein is conspicuous upon either side of the neck. Of the glandular 
masses, the salivary glands are the most conspicuous, although 
numerous lymph nodules are present. There are three pairs of 
salivary glands each gland connected by a slender duct with the 
mouth cavity. The thyroid (thyreoid) glands are in most forms 
closely applied to the lateral surface of the larynx and trachea. 

Add to the drawing already begun the ventral view of the thoracic 
and the neck viscera in situ. 

2. The Neural Cavity 1 and Its Contents in situ . 

Place the specimen with the dorsal surface up and remove the 
muscle masses from the lateral and posterior surfaces of the skull 

and from the dorsal surface of the vertebral column. With bone 

% 

forceps and strong scissors carefully remove the dome of the 
cranium bit by bit, and the dorsal portions of the consecutive 
vertebrae and thus lay open the neural cavity. In the cranial 
region observe the brain covered by the meninges which are con¬ 
tinuous throughout the whole neural cavity. The meninges may 
be removed to expose the dorsal surface of the brain. From this 
aspect the two cerebral hemispheres, the cerebellum and the 
posterior part of the medulla may be seen, the latter continuous 
posteriorly with the spinal cord which lies in the tubular spinal or 
vertebral region of the neural cavity. 

Draw a dorsal view of the animal showing the brain and spinal 
cord in situ. 

3. The Digestive System. (For comparison use demonstration 

preparations of other mammals and human manikins and 
models.) 

Preliminary Dissection. —To expose the anterior region of the 
digestive tract, the trachea, heart, and lungs must be removed. 
This is most conveniently done by lifting up the anterior region 

1 The dissection of the neural cavity should be made upon the first or second day, 
before the brain and spinal cord have begun to soften, or, if the specimen is to be 
preserved in formalin or alcohol, the cavity should be opened enough to permit the 
entrance of the preserving fluid. If the time is too short to admit of this dissection, 
it may be given by the teacher upon a fresh specimen as a demonstration. 


12 


MAMMALIAN ANATOMY 


of the trachea from its contact with the oesophagus and severing 
the trachea immediately posterior to the larynx. By using the 
cut end of the trachea as a stem and cutting the larger blood 
vessels from their connection with the heart, the whole set of 
organs to be removed may be detached from the membranes which 
hold them in place and lifted out as one mass. The oesophagus 
is thus exposed throughout its entire course, and may be seen to 
pass through the diaphragm and lead into the stomach. 

Turn the whole intestinal mass to one side and find the pos¬ 
terior region of the digestive tract which continues as the rectum 
through the dorsal region of the pelvic cavity to the anal orifice. 
Note that in this region, where the intestine takes a straight course, 
one sees clearly the typical relationship of the parietal and 
visceral portions of the peritoneum continuous with each other 
through the double layers of the mesentery. In the greatly elon¬ 
gated and convoluted region of the intestine the mesentery 
becomes correspondingly elongated along the edge where it joins 
the visceral peritoneum of the intestine so that it is like a very full 
ruffle bearing the intestine along its edge. Note the extensive 
branching of blood vessels which lie between its two layers. In 
regions where different portions of the mesentery come per¬ 
manently in contact extensive adhesions occur. 

Beginning with the rectum trace the whole course of the intes¬ 
tinal tract anteriorly (opposite to the direction of motion of its 
contents) freeing it little by little from its attachment to the 
mesentery until the vicinity of the stomach is reached. Leave the 
loop of the intestine into which the stomach leads, intact in con¬ 
nection with its mesentery. 

The parts of the digestive system may now be studied con¬ 
secutively from anterior to posterior end. Record by drawing. 

(The mouth, pharynx, and salivary glands will be studied in 
greater detail with the sheep’s head and other material later in the 
course.) • 

Note the extent of the oesophagus, the muscular character of 
its walls, and its collapsed condition when empty. 

Note that the stomach is a pouch-like expansion, the develop¬ 
ment of which has involved a rotation into a transverse position so 
that the mesentery of the stomach has formed a sac-like structure 


GENERAL ANATOMY OF THE MAMMALIAN BODY 


13 


which hangs posteriorly from the greater curvature of the stomach 
and is known as the great omentum. (Particularly well shown in 
the cat.) The spleen, which is not a part of the digestive system, 
is inclosed between the layers of the left hand portion of this 
structure; and the pancreas, an important digestive gland, which 
lies mainly between the layers of that portion of the mesentery 
which supports the first loop of the intestine, also pushes itself 
into the adjacent region of the omentum. Ventrally the stomach 
is suspended by a ventral mesentery, between the two layers of 
which the voluminous liver is located, so that one portion of the 
mesentery stretches between the stomach and the liver and is 
known as the lesser omentum, while the remaining portion 
stretches from the liver to the diaphragm and forms the falciform 
ligament. 

Look for a gall bladder (absent in some species) partly imbed¬ 
ded in the liver, and for a duct leading from this, or from the liver 
directly, to the first loop of the intestine into which it opens in 
close proximity to the opening of the pancreatic duct. 

Note the enormous length of the small intestine and compare it 
with the total length of body. The first loop, into which the 
stomach leads and the ducts from the liver and pancreas open, is 
known as the duodenum. Trace the small intestine posteriorly 
to the place where it opens into the side of the large intestine or 
colon. 

Note that the colon has a blind extension, the caecum, which is 
very wide and voluminous in the rodents (cf. cat and man). Do 
you find an appendix opening into this? Compare the total 
length of the colon with that of the small intestine. 

Remove and discard the entire abdominal portion of the 
digestive system leaving only a sufficient length of the rectum to 
serve as a landmark. 

4. The Urogenital System. (Cf. models showing relationships in 
the human body.) By exchanging specimens study both 
sexes, and record by means of a suitable drawing of each. 

The Urinary System. —Note the location of the kidneys dorsal 
to the parietal peritoneum and hence not actually in the abdomi¬ 
nal cavity. Look for the suprarenal gland slightly anterior to each 


14 


MAMMALIAN ANATOMY 


kidney, but not a part of the urinary system. Remove the peri¬ 
toneal covering of the kidneys and from each kidney trace the 
ureter which extends posteriorly, dorsal to the parietal peri¬ 
toneum, as a slender duct which leads into the dorsal region of the 
urinary bladder near its posterior end. To demonstrate this 
relationship the urinary bladder must be drawn forward. Note 
the ventral location of the bladder, and that it lies mainly pos¬ 
terior to and with its anterior surface covered by, the parietal 
peritoneum. 

Open the pelvic cavity by cutting through .the pubic arch a 
little to one side of the symphysis, after first carefully pushing 
aside, in case the animal is a male, the organs which lie ventral 
to the arch. Lay the pelvic cavity as widely open as possible by 
forcibly spreading apart the two halves of the pelvic girdle, and 
examine the contents of the cavity from the side. 

Note that in the pelvic cavity there are no serous membranes, 
and that the organs lie in a packing of areolar and adipose tissue. 
This packing should be carefully removed until the contours of 
the various pelvic organs can be fully seen. The most dorsal 
of these is the rectum, which may now be traced to the anal 
orifice, while the most ventral is the urethra which leads from the 
bladder to the external orifice in the ventral wall of the deep depres¬ 
sion known as the urogenital sinus of the female, while in the male 
the urethra takes a much more extensive course through the whole 
length of the penis, to reach the orifice. 

The Reproductive System. —In the female find the very small 
oval ovary upon each side posterior to the kidney and supported by 
a reduplicature of the peritoneum known as the mesovarium. 
From near the ovary a funnel-shaped orifice leads into a tiny coiled 
tube, the uterine tube or oviduct, which in turn leads into the 
anterior end of the corresponding arm of the Y-shaped uterus. All 
of these structures are supported by the mesovarium, which thus 
corresponds to the “ broad ligament ” of the human female. Trace 
the two arms of the uterus to their union posteriorly into the 
median portion and note that this is located dorsal to the bladder 
and ventral to the rectum in the pelvic cavity, and thus like these 
organs is posterior to the parietal peritoneum. The uterus leads 
into the thinner walled and more distensible tube, the vagina, 


GENERAL ANATOMY OF THE MAMMALIAN BODY 


15 


which passes posteriorly to the external orifice within the uro¬ 
genital sinus. 

In the male note that the testes are located ventral, i.e., 
external, to the pubic arch, where they lie in the scrotal sacs, a 
position which they have reached by descending from the abdomi¬ 
nal cavity through the inguinal canal (cf. the condition found in 
some young males, before this descent has occurred). Note that 
in this descent the testis has carried with it (1) certain muscul&r 
elements from the abdominal wall, forming the cremasteric 
muscle surrounding the testis within the scrotal sac, (2) a double 
layer of peritoneum, the outer derived from the parietal perito¬ 
neum in the inguinal region, the inner consisting of the reduplica- 
ture known as the mesorchium, in which the testis and its 
associated structures lie. Note the course of the ductus deferens 
anteriorly through the inguinal canal forming (together with the 
spermatic nerve, artery and vein), the spermatic cord; its dorsal 
and posterior course within the abdominal and pelvic cavities 
to reach the dorsal surface of the urethra into which it opens; the 
seminal vesicle, often very voluminous, which opens into the ure¬ 
thra in association with the ductus deferentia; accessory glands 
(increasing the liquid portion of the seminal fluid), consisting 
mainly of the prostate gland located at the junction of the two 
ductus deferentia, and the bulbourethral gland lying along the 
dorsal urethral wall; the penis, the distal portion of which is 
usually withdrawn within a reduplicature of skin known as the 
prepuce. 

Before finally discarding the specimen, remove the kidneys 
with a short length of the ureters attached and preserve in 5% 
formalin or in 70% alcohol for later study. 

D. THE PLAN OF THE BODY AS SHOWN IN TRANS¬ 
VERSE SECTIONS AND IN A MEDIAN SAGITTAL 
. SECTION. 

For the general plan of any vertebrate body, study a trans¬ 
verse section through the middle of the body (ccelomic region) of 
a dogfish, in which the relationships are less complicated than in 
the mammals. For camparison, study demonstration prepara¬ 
tions made by sawing through the frozen bodies of adult mammals, 


i6 


MAMMALIAN ANATOMY 


or by cutting with a sharp, thin knife the well-hardened bodies 
of embryos sufficiently advanced to show the typical form and 
arrangement of parts ( e.g., guinea-pig embryos measuring from 
7 to io cm. in length). These sections should include not only 
transverse sections through both the thoracic and the abdominal 
regions but also a median sagittal section to show the longitudinal 
extent and relationships of the parts studied. All these prepara¬ 
tions should be studied under water or 70% alcohol, and, in case 
embryos are used, they should be studied under a dissecting 
microscope. 

Study for the general plan of the body, especially the location 
and boundaries of the neural and coelomic cavities, and the 
relation of the serous membranes of the latter to the walls of the 
cavity and to the contained organs, with the identification of 
the latter. Note also, especially in the transverse sections, the dis¬ 
position of the muscle masses with relation to the skeleton, and 
compare these sections with certain familiar cuts of meat (e.g., 
loin and rib chops). 

Draw a transverse section through the body of the dogfish, and 
a median sagittal section through a mammalian body, adult or 
embryonic. If time permits draw also a good typical transverse 
section through the mammalian thoracic region and a similar section 
through the mammalian abdominal region. 


H. INTRODUCTORY HISTOLOGICAL STUDY 


For the names of the parts of the microscope and explanation 
of the optical principles involved in its use, the student should 
consult the small book which accompanies each instrument. 

V- 

Directions to be Observed in the Use of the Compound Micro¬ 
scope. 

1. Lift the microscope stand by handle arm, or by base. 
Remove dust. If necessary, clean the oculars and objectives, 
using for the purpose only pure tissue paper or soft clean linen, 
applied with a rotary motion. Always take the greatest of care to 
keep the microscope lenses clean, and free from contact with 
any object. 

2. See that all parts of the microscope stand are properly 
and firmly adjusted, and that the nosepiece, and the coarse and 
fine adjustments by means of which the microscope tube is raised 
and lowered, are in proper working order. Place the fine adjust¬ 
ment at about the middle point of its range of action. 

3. Place the microscope stand squarely upon the table with 
the pillar directly in front of you, taking care that the direct 
sunlight does not fall upon you or upon any part of the instrument. 
Adjust the height of your own seat so that you can look through 
the tube with ease. 

4. If the ocular and objectives are not already in place, adjust 
them as follows: Place an ocular in the upper end of the tube, and 
with the coarse adjustment sufficiently raised to prevent contact 
of the objectives with the stage, screw each firmly into its proper 
place in the nosepiece, finally bringing the low power objective 
into line at the lower end of the tube. 

5. Look through the tube (using one eye while the other is 
kept open), and turn the mirror in such a way that the best 
available white light is reflected through the aperture of the stage 
giving a white circular field of vision. Note that the light may 
be taken from any direction except from behind you, while the 
microscope remains squarely placed in front of you. 

17 


2 


i8 


MAMMALIAN ANATOMY 


6. Place upon the stage the slide upon which the preparation 
to be studied has been mounted (see p.19 ) with this preparation 
itself over the center of the aperture of the stage. 

7. Focus with the low power. Before doing this, lower the 
microscope tube, if necessary, by means of the coarse adjustment, 
until the lower end of the objective is about an eighth of an inch 
above the slide, watching the process carefully to see that the 
objective does not come in contact with the slide. Never lower 
the coarse adjustment while looking through the tube. Then, 
looking through the tube, with both eyes open, slowly raise the 
tube by means of the coarse adjustment until the outlines and 
details of the object can be sharply seen, the indication that the 
microscope is in focus. The focus may now be sharpened, and 
different levels of the object may be brought out by use of the 
fine adjustment. Never try to see what is not in focus. 

8. If a certain region is to be studied with greater detail, 
change from the low to the high power. In case the 
microscope you are using is parfocal, the following method 
should be used: 

With the low power objective in place, focus the microscope 
upon the object to be studied. Looking through the microscope, 
move the slide so as to bring into the middle of the field the detail 
which is to be studied under high power. Without changing the 
adjustments, turn the revolving nosepiece so as to bring the high- 
power objective into line with the microscope tube. A slight 
turning of the fine adjustment should now suffice to bring the 
object sharply into focus. In most microscopes the change from 
low to high power involves a slight downward focusing with the 
fine adjustment, but you should determine which direction is 
necessary with each instrument that you use by cautious experi¬ 
ment, while looking through the tube to see when the focus is 
sharp. Never use the coarse adjustment with the high power, 
but if the microscope gets out of focus turn back to the low power 
and start over again with the coarse adjustment. 

9. Remember that the microscope is an aid to vision, and if 
used properly with both eyes open and used alternately, and with 
frequent resting for a moment by looking off at some distant object, 
the microscope will never injure the eyesight. 


INTRODUCTORY HISTOLOGICAL STUDY 


19 


Preliminary Practice in Focusing and Using the Microscope. 

Examine, for this purpose, one of your own eyebrow hairs or 
an eyelash, mounted in a drop of water placed in the middle of 
a slide. In order to enclose this drop between two parallel sur¬ 
faces, it should be covered with a clean cover-slip. This must be 
applied with care in order that air bubbles shall not be included, or 
the upper surface of the cover-slip itself flooded with the water. 
To obviate these difficulties hold the cleaned cover-slip by one 
edge by means of the forceps and, applying the opposite edge of 
the cover-slip to the slide at the edge of the drop which is to be 
covered, gradually lower the cover-slip upon the drop. Inci¬ 
dentally it is advisable to make one mount with air bubbles 
included and use these also as objects for study under the 
microscope. 

Study the hair, thus mounted, under low power for its general 
form and proportion, recording these by means of a carefully 
planned drawing of the whole hair. Then select some one region, 
the location of which should be indicated upon the drawing of 
the hair as a whole, for the study of the minute details under the 
high power. Note that owing to the thickness of the object, the 
details studied must be selected with great care by focusing upon 
some definitely determined plane or surface. Draw the details 
thus studied. 

For further practice a few fibers of cotton, linen, wool, and 
silk may be successively examined, mounted as above directed. 

Draw carefully each object examined with sufficient detail to 
distinguish them from each other and to enable you to recognize such 
objects if at any time they become accidentally included in your 
preparations of other material. 

A. FRESH MATERIAL, SHOWING CELLS IN A CONDI¬ 
TION AS NEARLY AS POSSIBLE TO THAT WHEN 
LIVING. 

Throughout the following study keep always in mind the fact 
that cells are three dimensional objects and that a correct idea of 
their forms cannot be gained from a single aspect. Look, there¬ 
fore, for cells in various positions. Try to turn cells from one 
position to another by gently pushing the cover-slip along while 


20 


MAMMALIAN ANATOMY 


you have the cells under observation in the microscope field. 
When a clear conception of the shape of a given variety of cell 
has been gained, make a model of it in plastilina before attempting 
to draw individual cells. 

Finally record your study of each variety of cell by suitable 
drawings in which the form of the cell as seen from various aspects 
is shown. Make these drawings on a large scale so that the essen¬ 
tial parts of the cell, nucleus and cytoplasm, may be shown with 
whatever structural details may be peculiar to that type of cell. 
If the material is such that the arrangement of the cells with relation to 
each other is shown, this also should be studied and recorded. 

i. Cells from Animal Tissues. 

Epithelial Cells Scraped from the Inside of the Cheek. —Mount 
this material in a drop of physiological, or normal, salt solution 
(.6% to .8% sodium chloride in water, the percentage of this salt 
which occurs in animal tissues). Cover with a cover-slip as above 
directed, and examine first under low, then under high power, 
shutting down the illumination as may be needed to bring out 
well the details. Note the colorless, transparent nature of proto¬ 
plasm. The preparation may be stained on the slide under the 
cover-slip as follows: Place on the slide, in contact with the edge 
of the cover-slip, a drop of stain to be used, which must be in an 
aqueous medium when, as in this case, the material is in water or 
in an aqueous solution (methylene blue is frequently used for 
fresh or living material). At the opposite edge of the cover-slip 
lay a small fragment of filter paper with its edge in contact with 
the fluid in which the material is mounted, thereby drawing out 
this fluid and allowing the stain to enter. The excess of stain may 
be removed later by reversing the process. In any case supply 
some fluid at the edge of the cover-slip sufficiently frequently to 
prevent the preparation from drying. An aqueous solution of 
glycerine (50%) may be used to good advantage for this purpose, 
since it not only does not dry but also renders the preparation 
more transparent. 

Study the unstained and stained preparations to determine the 
shape and arrangement of the cells, seeking for this purpose cells 
in small groups of not more than four or five. Note the deeply 


INTRODUCTORY HISTOLOGICAL STUDY 


21 


staining nucleus, the surrounding cytoplasm, and the thin and 
delicate cell membrane, with the numerous imprints made upon 
it by adjoining cells. 

Liver Cells. —Use a tiny fragment taken from the freshly cut 
surface of perfectly fresh liver (salamander or small mammal 
recommended). Place this in a drop of physiological salt solution 
upon a clean slide and break it up as much as possible by means of 
mounted needles or fine pointed forceps, thereby making a 
“teased” preparation. Add a cover-slip and then by pressing 
gently upon its surface with the spread points of a pair of forceps, 
further dissociate and spread the material. Study the small 
groups of cells which will lie around the edges of the larger masses. 
Stain with methylene blue. Note in addition to the typical parts 
of the cell, a great abundance of granules many of which escape 
from those cells which have been torn and are thus distributed 
through the preparation, at first masking the cells themselves. 
Note form and size of the cells as compared with those from the 
mouth epithelium. 

Red Blood Cells of Some Amphibian (Salamander or Frog).— 

Mount a little of the blood in a drop of physiological salt solution. 
Cover and study the preparation, staining it with methylene blue 
as in the previous cases. Note that these cells are isolated and 
hence do not show the impress of contact with other cells. Note 
the pale yellow color of the cytoplasm, and the colorless nucleus 
which takes the methylene blue stain readily. Determine the 
the shape of the cell by careful focusing with the fine adjustment, 
and by observing cells in different positions. The cells soon 
become shriveled and distorted, so that fresh mounts should be 

made when needed. 

$ 

2. Cells from Plant Tissues. 

Spirogyra or Some Similar Alga Showing the Arrangement of 
Cells in a Single Row.— Mount in water and cover with cover- 
slip. Note the green chlorophyl, the starch granules associated 
with it and stained a deep blue by application of a weak solution 
of iodine in an aqueous solution of potassium iodide (which at the 
same time stains the nucleus brown, an illustration of differential 
staining), the large vacuoles, and the relatively small amount of 


22 


MAMMALIAN ANATOMY 


cytoplasm in delicate strands. Note the thick cell wall of 
cellulose. 

Epidermic Cells from an Onion Bulb, Showing the Arrange¬ 
ment of Cells in a Single Layer Covering a Surface. —Mount in 
water. Stain with methylene blue and study all parts and their 
relations with care. 

A Thin Section of Potato Cut by Hand with a Section Knife 
and Illustrating the Arrangement of Cells in a Mass. —Mount in 

water. Note large size of cells, large amount of stored starch 
granules within the cell. These are brought out well by staining 
with iodine. They usually obscure the nucleus. 

B. HISTOLOGICAL SECTIONS, A METHOD OF PRE¬ 
PARING MATERIAL FOR MICROSCOPIC STUDY. 

Remove from a recently killed animal as soon as possible after 
death, small pieces of the desired tissues 1 and prepare them for 
sectioning, by the following method: 

Killing and Fixing. 2 —Place the fresh material in pieces not 
larger than a centimeter in the greatest dimension, in a consider¬ 
able quantity of the following fixing fluid for from four to sixteen 
hours according to size: 

Bouin’s Fixative. 

Parts 


Picric acid, saturate aqueous solution.,. 75 

Formaline (40% formaldehyde)... 25 

Glacial acetic acid. 5 


1 It is recommended that at this time each student begin the preparation of a 
piece of material mainly for later sectioning in connection with the study of various 
tissues and organs. Young mammals (kittens or rabbits for example) afford excel¬ 
lent material. It is also recommended that Necturus or some other amphibian be 
used, as the large size and primitive relationships of its cells render it excellent 
material for the beginning student. The following tissues and organs will prove of 
use in later work in the course: From Necturus, cartilage, voluntary muscle, intes¬ 
tine, liver; from some mammal, costal cartilage, voluntary muscle, intestine, liver, 
salivary gland, ovary, testis, artery, vein. It is possible also to obtain satisfactory 
results by making transverse sections through the trunk region of a half grown 
salamander larva, since these sections furnish excellent material for the review of the 
general plan of the vertebrate body, while at the same time affording an opportunity' 
for the examination of a variety of tissues and organs. 

2 The length of time which material should be left in any given fixative, and the 
subsequent treatment after fixation, are matters which vary with the nature of the 
fixative itself. Directions concerning these matters should therefore always be 
carefully heeded and faithfully followed. 






INTRODUCTORY HISTOLOGICAL STUDY 


23 


This, like any efficient killing and fixing reagent, preserves the 
cells without either shrinking or swelling the parts, and holds the 

various cell structures in as nearly as possible the same relation¬ 
ships that they possessed in life. From this fixing reagent the 
pieces must be transferred without undue handling to 50% alcohol 1 
which should be changed after an hour or two to 70% alcohol. 
Several changes of 70% alcohol are desirable before the material 
is finally left in this or a somewhat higher grade of alcohol (80%) 
until further use is to be made of it. 

Decalcifying. —In case the material contains any calcarious 
deposit (as, for example, would be the case with bone) it is neces¬ 
sary that this calcarious matter be removed. A reagent com¬ 
monly used for this purpose is a saturate aqueous solution of 
picric acid to which a sufficient amount of nitric acid is added to 
make about 1%. In order to transfer the material to this solu¬ 
tion it is necessary to gradually replace the 70% alcohol in which 
it is preserved, by water, and for this purpose the material is 
transferred successively to weaker grades of alcohol (55%, 40%, 
20%) and finally to water. 

As a general rule to insure the desired replacement of one fluid 
by another, the.material should be left in each new fluid for from 
a half hour to an hour for each millimeter of the shortest dimen¬ 
sion of the object.. It should always be kept in mind that water 
and grades of alcohol below 70% tend to injure tissues by soften¬ 
ing them and thus prolonged exposure to these fluids should 
always be avoided. 

From water the material is placed in the decalcifying fluid 
where it should remain for 24 hours or longer. 

It must then have the excess of picric acid removed by wash¬ 
ing in several changes of water, after which it is passed through 
the successive grades of alcohol until 70% alcohol is reached. 

1 To mix any grade of alcohol from any higher grade: Take as many units of the 
higher grade as are equal to the percentage of the desired lower grade, and add to it 
enough water to make of the mixture as many units as are equal to the percentage 
of the higher grade. For example, to mix 70% alcohol from 95%, take 70 c.c. of 
the 95% alcohol and add 25 c.c. of water. 95% alcohol (i.e., commercial alcohol) 
is the grade from which the lower grades are usually obtained; 100% alcohol 
is very expensive and hence must always be used sparingly , and never used to mix 
with water for the lower grades of alcohol. 



24 MAMMALIAN ANATOMY 

Dehydrating. —In order to use the material, thus hardened 
and preserved, for microscopic sections it must first have all the 
water removed from it by the successive transfer to higher grades 
of alcohol until 100% (absolute) alcohol 1 is reached. Thus from 
70% alcohol in which it is preserved (and may be kept indefinitely 
until needed), it must be transferred to 95% in which it should 
remain for several hours, and from this to 100% in which it should 
be kept for only a few hours at the longest, as this tends to harden 
and shrivel the tissues. 

Clearing. —This process consists in replacing the alcohol with 
some oil (usually xylol or turpentine) which, being on the one 
hand miscible with absolute alcohol, will replace it, while on the 
other hand it is a solvent of the paraffine in which the material 
must later be imbedded, and may thus be readily replaced in turn 
by the paraffine. The material is placed in the clearing oil and 
allowed to remain until its transparent appearance, when sub¬ 
jected to a strong transmitted light, indicates that the oil has 
quite replaced the alcohol. In the clearing oil the material may 
be kept indefinitely, though a prolonged stay in this medium is 
likely to render it brittle. 

Imbedding. —This requires the use of a paraffine oven or other • 
device for keeping melted paraffine at a uniform temperature 
slightly above the melting point of the paraffine used (54°-56° 
centigrade). 2 Place the cleared tissue in the melted paraffine 
and leave it for a sufficient length of time to insure the com¬ 
plete replacement of the clearing oil by the paraffine which will 
thus impregnate the material. The process requires about half 
an hour for each millimeter of thickness (least dimension). When 
the tissue is to be removed from the paraffine, have in readiness 
all of the articles and implements which may be needed, for the 
paraffine hardens quickly and the transfer must be made before 
the hardening begins. 

1 Acetone may be substituted in this and subsequent processes for 100% alcohol. 

2 A very simple and convenient device for student use consists of a jelly tumbler 
which is first filled two-thirds full of melted paraffine and set aside to harden, after 
which it may be used at any time by melting the top to a depth of about an inch by 
bringing directly over it an ordinary electric light bulb. So long as the material to 
be imbedded rests upon the solid surface of the lower paraffine it is in no danger from 
overheating, and the amount of melting may be regulated by raising and lowering 
the electric light bulb. 


I 


INTRODUCTORY HISTOLOGICAL STUDY 


2 5 


Prepare a watch crystal or other small container by smearing 
its inner surface with glycerine. Pour into it enough melted par¬ 
affine to amply cover the piece of material which is to be imbedded. 
Transfer the material to this container by means of a slightly 
warmed section lifter or a strip of stiff paper. Before the par¬ 
affine begins to solidify, adjust the material to any desired posi¬ 
tion by means of a warmed instrument, and if more paraffine is 
needed it may be added. The material should not be in the least 
disturbed, however, after the paraffine has begun to solidify. 
Cool the paraffine rapidly by gently blowing across the surface 
and at the same time gradually lower the container into a dish of 
cold water, carrying it under the surface of the water as soon as 
the paraffine is hard enough to stand the pressure. Leave it under 
the water until the paraffine is thoroughly hardened. 

Sectioning. —The block of paraffine in which the material is 
imbedded should be shaved down to a rectilinear form a little 
larger than the imbedded mass, and should be securely fastened 
by means of melted paraffine upon a cork or other device for 
holding it, taking care to so orient it as to obtain sections in what¬ 
ever plane is desired. Adjust the block to the microtome with 
the edge of the knife parallel with two edges of the block in such a 
way that the knife will pass through the shorter dimension of the 
object. Cut sections of the desired thickness, about io or 15 
micra (a micron is .001 mm.), for ordinary study. 

Spreading Sections on Slide. —These sections, which must be 
handled with the greatest of care by means of forceps or a camePs- 
hair brush, should be placed upon the middle of a microscope slide, 
which has been previously smeared with albumen fixative, 1 thor¬ 
oughly rubbed in. 

The sections, if not wrinkled, may then be fastened to the slide 
by gently warming the preparation, holding the slide high above 
the alcohol flame, until the paraffine surrounding the section 
shows signs of being about to melt. 

If the sections are wrinkled, place a drop of water in contact 
with them before warming the slide. This drop will run under 

1 Albumen fixative may be conveniently prepared by mixing thoroughly equal 
parts of filtered white of egg and glycerine, and adding a little sodium salicylate 
or a few crystals of thymol as a preservative. 


26 


MAMMALIAN ANATOMY 


and float the sections, and the subsequent warming should 
continue until all wrinkles disappear, more water being 
added from time to time if needed, and care being taken not 
to melt the paraffine. The excess of water may then be 
removed with a bit of filter paper, and the slide set aside for 
24 hours to dry. Keep the identity of the slide by means of a 
temporary label. 

Staining and Mounting Sections on Slide. —After the slide is 
dry, remove the paraffine from the sections by first gently warming 
the slide over an alcohol flame until the paraffine begins to melt, 
and then placing the slide for a minute or two in a staining jar 
of xylol, which will dissolve the paraffine. As the stain which is 
to be used is an aqueous solution, with which, of course, oil will 
not mix, the xylol should be removed by placing the slide in a 
staining jar of 100% alcohol for a few minutes, first draining off 
the excess of xylol upon a piece of filter paper. 

From the 100% alcohol transfer the slide to a jar of 95% 
alcohol, and from this, without draining off the excess of alcohol, 
carry the slide in a horizontal position into a large, shallow dish 
of clean tap water in which it should be moved very slowly back 
and forth until all milkiness disappears and the water runs freely 
from the surface when the slide is lifted out of it. 

The sections are now impregnated with water and will take 
an aqueous stain. Place the slide in a jar of this stain (hema¬ 
toxylin, in this case) and leave it until a decided but not dark 
color has been imparted to it. From time to time take the slide 
out of the stain and rinse it in the water to see how deep a color 
has been acquired (cf. with the “sample” slide furnished by the 
laboratory). This process may take from one to ten minutes 
and must be carefully watched by the student that overstaining 
may not occur. 

When the staining is completed, carefully transfer the slide 
in a horizontal position, to the dish of tap water, where it should 
be left a few minutes in order that the slight alkalinity which tap 
water usually possesses, may change the reddish tinge of the 
sections to a bluish purple. Drain and wipe off the excess of water 
from the slide, and transfer the slide successively to 95 % and 100% 
alcohol, to dehydrate it. 


INTRODUCTORY HISTOLOGICAL STUDY 


27 


Then place the slide in the jar of xylol to remove the alcohol 
and render the stained sections transparent. There should be 
no milkiness in slide or surrounding fluid at this stage. 

When the sections are perfectly transparent (i.e., cleared) 
remove the slide from the xylol, drain and wipe off the excess of 
xylol, place a drop of Canada balsam on the sections and cover 
carefully with a perfectly clean cover-slip. Label the slide with 
the name of the structure sectioned and with your own name 
together with other data such as the direction of the section, thick¬ 
ness of section, stain, etc. Leave in a horizontal position until 
the balsam is hard, taking care never to pile slides upon each other. 

C. PERMANENT MOUNTS (DEM. SL. COLL. 1 ) SHOWING 
EXAMPLES OF CELLS FROM DIFFERENT TISSUES. 

Study each preparation with care, noting in each case the 
source of the material, and the method of preparation which has 
been employed. Make drawings to show your conception of each 
type of cell studied with the arrangement of cells when this is shown 
by the preparation . 

Cells of Epithelial Tissue, Showing the Characteristic Arrange¬ 
ment of Cells to Form a Continuous Layer. — (E.g., a surface mount 
of the outer layer of epidermis of a salamander or frog obtained 
from a recent moult.) 

Cells of Skeletal Tissue, howing the Characteristic Wide 
Separation of the Cells by Intercellular Material.— (E.g., a section 
of 10-15 mm. pig embryo showing embryonal skeletal tissue with 
stellate cells.) 

Cells of Muscle Tissue, Showing the Characteristic Elon¬ 
gated Form of Contractile Cells.- — (.Eg., a teased preparation of 
smooth muscle tissue from the muscle coat of the intestine of a 
cat.) 

Cells of Nerve Tissue, Showing the Characteristic Branched 
Form of Cells with Wide Separation of the Cell Bodies.— (E.g., 

1 The term Demonstration Slide Collection (Dem. SI. Coll.) is used to designate 
such slides as may most advisably be arranged by the teacher for the students to 
examine, rather than given out to the students. It is recommended that such a slide 
be accompanied always by an adequate explanation or diagram, or by a suitable 
reference to some text-book of histology. 


28 


MAMMALIAN ANATOMY 


a smear preparation 1 from the gray nerve substance of the spinal 
cord of the pig.) 

Reproductive Cells, not Forming a Tissue in the True 
Sense. — (E.g., growing ova, in place, in sections of a mammalian 
ovary.) 

D. PERMANENT MOUNTS SHOWING CELL DIVISION BY 

MITOSIS. 

Study slides (Lab. SI. Coll.) 2 which show the cells of some 
tissue in which rapid growth is in progress, where, among the 
ordinary “resting” cells of the tissue certain cells may be found 
which are in the process of mitosis. (E.g., sections through the 
growing tips of onion roots; or through the epidermis of salaman¬ 
der larvae; or surface mounts of the thin epidermis (conjunctiva) 
stripped off from the front of the eye of a salamander.) 

Use for comparison other preparations (Dem. SI. Coll.) 
showing details of mitosis. 

In each case examine first the resting cells and note the relation 
of cytoplasm and nucleus, and the presence of the deeply staining 
granules of chromatin within the latter. In the case of the 
dividing cells search for as many stages of the process and as many 
aspects of the mitotic figure as possible. Note the temporary 
disappearance of the nucleus as a distinct structure; the trans¬ 
formation of the chromatin of the nucleus into chromosomes which 
are ultimately to be split and distributed equally to the two daugh¬ 
ter cells, to eventually enter into the reconstruction of the nuclei 
of these cells; the separation of the cytoplasm into two masses 
surrounding the respective nuclei. Make suitable drawings to 
record this study. 

E. VARIETIES OF EPITHELIAL TISSUES. 

Study slides (Lab. SI. Coll.) showing a variety of epithelial 
tissues. In each case try to understand first the relation of the 
epithelium in question to the structure of the organ of which it is a 
part. Determine whether the plane of the preparation is at right 

1 For this method of making preparations for histological study, see p. 59. 

2 By the designation Laboratory Slide Collection (Lab. SI. Coll.) is meant a set of 
duplicate slides which the students use individually for study as they would do with 
their own preparations, had they the time and skill to make them. 



INTRODUCTORY HISTOLOGICAL STUDY 


2 9 


angles to the free surface (: i.e a vertical section of the epithelium) 
or is parallel with the free surface (i.e., either a tangential section 
of the epithelium or a surface mount). Keep in mind the fact 
that in order to understand the shape and arrangement of the 
cells it is necessary to study them from both aspects. In case of a 
vertical section note the sharp delimitation of the epithelium from 
the connective tissue upon which it rests. Consider whether the 
arrangement is in one layer (simple epithelium) or more than one 
(stratified epithelium) ; what the prevailing shape of the cells is 
(squamous, cuboidal, or columnar) ; and whether there are indica¬ 
tions of cells with special functions (protective, secretory, or 
motile). Record by suitable drawings on a sufficiently large scale 
to show the parts of the individual cells, as well as their arrangement. 

The following preparations (Lab. SI. Coll.) are suggested for 
the study of epithelial structures although others equally good may 
be added or substituted. 

1. Sections of the gall bladder of Necturus showing a lining of 
simple cuboidal epithelium seen mainly in vertical section, though 
limited regions may be cut tangentially. 

2. Transverse sections through the stomach and gastric 
diverticula of a grasshopper showing in vertical section a lining of 
simple columnar epithelium. 

3. Transverse sections through the intestine of some lower 
vertebrate (e.g., Necturus) showing in vertical section a lining 
of simple columnar epithelium, with numerous secretory cells 
(mucous cells) among the cells of more general character; and an 
outer covering (visceral peritoneal layer or serosa) of simple 
squamous epithelium also in vertical section. 

4. Sections through the coiled oviduct of a mammal showing a 
simple ciliated columnar epithelium, mainly in vertical section. 

5. Surface mounts of the mesentery showing the simple 
squamous epithelium of a serous membrane. 

6. Transverse sections of the oesophagus of a lungless sala¬ 
mander (e.g., Desmognathus or Eurycea) showing in vertical sec¬ 
tion a stratified columnar epithelial lining only two cells thick, 
with both secretory (mucous) and motile (ciliated) cells. 

7. Vertical and tangential sections through the skin of young 
salamander larvae (e.g., Desmognathus or Eurycea) showing an 


30 


MAMMALIAN ANATOMY 


epidermis composed of a stratified cuboidal epithelium only two 
cells thick. Note the thick cuticular border of the cells of the 
outer layer and the numerous distended secretory cells of the 
inner layer. 

8. Vertical and tangential sections through an unpigmented 
region of the skin of an adult salamander (e.g., Desmognathus or 
Eurycea) showing an epidermis composed of a stratified epithelium 
of several layers, the outer squamous in form ( cf. surface mounts 
of conjunctiva used for mitosis, p. 28) while numerous multi¬ 
cellular alveolar or acinous glands will be seen to lie below the 
general level of the epidermis, through which their slender ducts 
pass to reach the external surface. 

9. Surface mounts of small pieces of the moult of an adult 
salamander showing the external layer of squamous cells which 
have thus been cast off. Look for gland pores in this. 

ro. Vertical sections through the skin of a human fetus show¬ 
ing an epidermis composed of stratified epithelium of many layers, 
the outer squamous in form. If developing sweat glands and 
hairs are present in the sections, note their relation to the deeper 
layers of epithelial cells. 

11. Vertical section through the lining of the mouth of some 
mammal showing a stratified epithelium of many layers, the outer 
squamous in form. (Cf. study of fresh cells scraped from the 
inside of the human mouth, p. 20.) 

12. Transverse section through the mammalian oesophagus 
showing a vertical section through its much folded squamous 
epithelial lining. 


III. DISSECTION OF THE FOOT OF THE PIG FOR THE 
MACROSCOPIC STUDY OF SKELETAL TISSUES 


Material. —Fresh material obtained from the abattoir. Both 
anterior and posterior appendages may be used; they should be 
amputated well above the carpus (or tarsus). Skeletons of the 
appendages of pig and other ungulates (e.g., sheep, cow, horse) 
and of man. 

Preliminary Examination. —Determine by comparison with 
skeletons of related forms whether specimen is posterior or 
anterior, and right or left. Note that the epidermis, possibly 
including the hoofs (nails) has been scraped off. By palpation 
identify the various bones and joints present. Determine the 
level of amputation, and study and identify so far as possible the 
structures shown in the cross section. Distinguish between the 
sections of the flexor and extensor groups of muscles (or tendons). 

Compare the foot with the corresponding appendage in other 
ungulates, both odd and even toed, and also in man, as to (i) 
number of digits; (2) extent of surface in contact with the ground 
(ungulate type as compared with plantigrade type); (3) extent 
to which adjoining toes are fastened together, preventing the 
spread of the digits; (4) range of motion of each joint. 

In making the comparison with the human foot note particu¬ 
larly in the ungulate foot the attempt at bilateral symmetry, 
the typical quadrupedal elevation of the heel process, and the 
total absence of anything resembling the longitudinal arch of the 
human foot. Which has the more primitive foot, the pig or 
man? In what line has each specialized and why? 

Summary of the varieties of skeletal tissues which will be met 
in the dissection. 

1. Tensile or Connective Tissue. 

Areolar or loose connective tissue, in many regions transformed 
to fatty or adipose tissue. 

Dense connective tissue, wholly of the fibrous variety. 

31 


32 


MAMMALIAN ANATOMY 


Membranous ( e.g., fasciae, sheaths of tendons, periosteum). 

Fascicular (e.g., tendons and ligaments). 

2. Rigid Tissues. 

Cartilage (e.g., hyaline cartilage, fibro-cartilage). 

Bone. 

Note and record, as the dissection progresses, the physical 
properties of each of the above tissues. 

Method of Dissection. —Remove the skin from the entire 
foot, being careful in the vicinity of the hoofs not to cut the under¬ 
lying parts. Dissect first from the extensor side. By cutting 
through the sheaths of the tendons and their ligamentous loops 
(annular ligaments), expose the fresh glistening surface of the 
tendons and follow them to their ultimate insertion into the bones. 
Note that, in making this insertion, the tendon fibers spread out 
and actually enter into the formation of the sheath of the bone 
(the periosteum). 

Similarly dissect from the flexor side, noting that here portions 
of the distal ends of the muscles are present; also that the tendons 
are much more deeply located, and that therefore their dissection 
involves, throughout, the removal of much more loose connective 
and adipose tissue, which on the flexor surface of the digits assumes 
the form of definite pad-like structures (“walking pads”)* In 
the dissection of the flexor side, work out the general course of 
two sets of flexor tendons into each digit. Following these out in 
detail into one of the larger digits, note that the more superficial 
one eventually divides over the metacarpo-phalangeal (metatarso¬ 
phalangeal) joint into two slips, which allow the deeper tendon to 
pass between them to its more distal insertion. Trace both the 
superficial and the deeper tendons to their insertion. Note in 
connection with the metacarpo-phalangeal (metatarso-phalangeal) 
joint the development of sesamoid cartilages (fibro-cartilage) and 
sesamoid bones. 

Dissecting still more deeply upon the extensor side, study the 
various joint structures. Note the arrangement of the external 
band ligaments; the continuity of the periosteum of each bone 
concerned in the joint into a loose joint capsule which entirely 
encloses the joint; the smooth, moist synovial membrane which 


DISSECTION OF THE FOOT OF THE PIG 


33 


lines the joint capsule; the lubricating “joint oil,” or synovia, 
within the joint cavity; the thin layer of hyaline articular cartilage 
which covers the bone, thus forming the frictionless articular 
surface; internal band ligaments in certain of the intercarpal 
(intertarsal) joints. 

If time permits, skeletonize your specimen, either by dissec¬ 
tion, leaving the ligaments which hold the bones together; or by 
the prolonged application of steam which may be led from an 
ordinary steam-pipe into a tightly closed receptacle containing 
the foot; or by prolonged boiling. In case either of the two latter 
methods be used, a chemical hood is recommended. Note at 
various stages of the process the effect of the moist heat upon the 
texture and appearance of the various skeletal tissues. The 
skeletonized material may finally be dried and preserved 
indefinitely. 


3 


IV. HISTOLOGY OF SKELETAL TISSUES 


A. TENSILE OR CONNECTIVE TISSUES. 

i. Loose Forms. 

Make a preparation of fresh areolar tissue by spreading out on 
a slide by means of mounted needles, a little of the subcutaneous 
connective tissue or intermuscular septum from any available 
mammal {e.g., cat or rabbit) and when the film thus spread is dry 
enough to remain in place, add a drop of physiological salt solution 
and cover with a cover-slip. Select a thin region of the prepara¬ 
tion. Examine first with low power, and then with high power. 
Note large amount of intercellular substance in the form of 
collagenous fibers and elastic strands. The fibers occur always in 
bundles and are often so fine and delicate that the high power 
must be used to bring out the component fibers of a bundle. The 
bundles usually appear in wavy lines, and frequently branch, 
although the individual fibers do not branch. The elastic strands 
are highly refractive in character, and by their abundant branch¬ 
ing and anastomosing form a reticulum. 

Irrigating the preparation under the cover-slip with a 2% solu¬ 
tion of glacial acetic acid serves to render the elastic reticulum 
more conspicuous, since the acid swells the bundles of collagenous 
fibers and causes them to gradually disappear from view. The 
nuclei of the scattered cells of the tissue may also become more 
conspicuous under the action of the acid. 

To bring the cells more clearly into view, the preparation may 
now be stained under the cover-slip with methylene blue, or a 
fresh preparation may be made and thus stained. Note the irreg¬ 
ular form of the cells, which are mainly of the lamellar type. 
Can you determine any definite relationship of the cells to either 
of the intercellular structures? 

Make drawings to show clearly your conception of each sort of 
intercellular structure of areolar tissue and the relation of the cells to 
these. 


34 


HISTOLOGY OF SKELETAL TISSUES 


35 


For comparison study permanent preparations ( e.g., cross 
sections of the intestine) in which areolar tissue may be seen in 
place in its relation to the other tissues which make up the organ. 
Record by drawing. 

Examine permanent preparations (Lab. SI. Coll.) of adipose 
tissue (e.g., in toto mounts of thin fatty deposits in the mesentery). 
Note that the cells have become enormously distended and spher¬ 
ical in form by the accumulation of fat which has crowded the 
nucleus and cytoplasm to one side of the cell. Draw a few of 
these fat cells. 

2. Dense Forms. 

As an example of the fibrous fascicular variety study per¬ 
manent preparations (Lab. SI. Coll.) of tendons. Note that in 
the longitudinal section the intercellular substance is seen to 
consist of large bundles of fibers arranged parallel to each other, 
with the cells flattened into the spaces between, and thus appear¬ 
ing in rows. Transverse sections of tendon show the cut ends of 
the large bundles of fibers delimited by the plate-like cytoplasmic 
processes of the lamellar cells which are crowded into the angles 
between the bundles. The septa which may be seen to separate 
the different portions of the tendon are of areolar tissue. Make 
such drawings of sections of tendon as will clearly show your concep¬ 
tion of the structure of this variety of tensile tissue. 

As an example of the elastic variety of tensile tissue study per¬ 
manent preparations (Lab. SI. Coll.) of an elastic ligament 
(e.g., the ligamentum nuchae). In a teased preparation or in 
longitudinal section note that the bulk of the structure consists 
of a heavy reticulum of elastic strands with narrow elongated 
meshes. In transverse section the highly refractive appearance 
of the cut ends of the elastic strands will be noted, as well as the 
scattered cells which lie among the delicate bundles of white 
fibers which fill the meshes of the reticulum. Make such drawings 
as will show the structure of the elastic variety of tensile tissue. 

B. RIGID TISSUES, 
i. Cartilage. 

Mount in physiological salt solution a thin transverse section of 
fresh hyalin cartilage (e.g., costal cartilage of some young mam- 


36 


MAMMALIAN ANATOMY 


mal). Such sections should be made by hand with a section 
knife, the piece of cartilage being held firmly between two pieces 
of pith, through which the knife passes in making the section. If 
several such sections are made rapidly and allowed to fall into a 
dish of the salt solution, among these, one will be likely to be thin 
enough to use. 

Examine under both low and high power, selecting particu¬ 
larly the growing region near the periphery. Note that the 
rounded cartilage cells are arranged in groups, each cell and each 
group surrounded by a capsule, which in its outer boundary blends 
with the capsules of other groups, thus contributing to a hyaline 
intercellular matrix. 

Study permanent preparations (Lab. SI. Coll.) of stained 
sections of hyalin cartilage to demonstrate the above-mentioned 
structures. Record your observations by suitable drawings. 

For comparison study and draw sections (Lab. SI. Coll.) 
of fibro cartilage ( e.g ., intervertebral cartilage). Note that the 
cells are of the typical cartilage nature with hyalin capsules, but 
that the intercellular substance includes numerous bundles of 
collagenous fibers like those of connective tissue. 

Similarly study and draw sections (Lab. SI. Coll.) of elastic 
cartilage (e.g., the cartilage of the external ear). Note that in the 
hyalin matrix which lies between the groups of typical cartilage 
cells, there is a reticulum of elastic strands with the highly 
refractive appearance characteristic of these. 

2. Bone. 

Study a transverse section (Lab. SI. Coll.) through the dense 
bone which forms the shaft of a long bone of some small mammal, 
decalcified and stained. Study under low power for general 
topography, noting the periosteum which forms its outer covering 
and the mass of cells of various types which fills its marrow cavity. 
Note that in the bony tissue itself the intercellular substance 
consists of systems of parallel lamellae which follow the direction of 
(i) the outer surface of the bone (peripheral lamellae); (2) the 
boundary of the marrow cavity (medullary lamellae); and (3) the 
Haversian canals .through which the blood vessels and nerves reach 
the various parts of the bone (Haversian systems of lamellae); and 


HISTOLOGY OF SKELETAL TISSUES 


37 


that there are (4) systems of lamellae irregularly placed filling in the 
angles between the other systems (interstitial lamellae). Note 
that the lines of bone cells indicate the boundaries of adjacent 
lamellae. 

Under the high power study the details of the bone cells, the 
flattened, nucleated bodies of which occupy crevices or lacunae 
between the lamellae, while the intricately branching cytoplasmic 
processes project into minute canals (canaliculi) which traverse 
the thickness of the lamellae and thus make possible an actual 
anastomosis of the branches of neighboring cells. (Schmorl’s 
method of staining which renders the bone cells reddish purple 
and the lamellae yellow, is especially good for the study of these 
details.) 

For comparison study under both low and high power an 
unstained dry transverse section through the shaft of a long bone 
(Lab. SI. Coll.). Note that the method of preparation has 
removed all of the soft parts so that the Haversian canals, lacunae, 
and canaliculi appear as empty spaces. 

Examine a longitudinal section through the shaft of a long 
bone, unstained dry preparation (Lab. SI. Coll.), and identify 
from this new point of view the structures already studied in the 
transverse sections. 

Record the above mentioned facts by drawings (1) of a sector of a 
transverse section passing from the periphery of the bone to the 
marrow cavity , showing the various systems of lamellce; (2) of three 
adjoining lamellce with lacunce and canaliculi as seen under the 
high power; and (3) of a few bone cells showing the details of their 
branches. 

Study a longitudinal section through developing bone, showing 
the formation of bone from cartilage (Lab. SI. Coll.). Study first 
with the naked eye or with a dissecting microscope and note that 
the section passes through the cartilaginous head of a long bone 
which is undergoing ossification. Draw on a large scale an outline 
of the whole section and fill this in with as many of the details of 
structure as you are able to identify in the following microscopic 
study. 

Under low power study the various regions, beginning with the 
typical hyalin cartilage. Note the arrangement of the cartilage 


38 


MAMMALIAN ANATOMY 


cells in columns as the line of ossification is approached, and the 
disappearance of the hyalin matrix between the cells in the region 
of bone formation. 

Note the small, deeply staining osteoblasts disposed in a layer 
lining the cavities thus formed, and the layers of intercellular 
substance which they are forming. Those osteoblasts which 
become included between the layers or lamellae become the bone 
cells. Look for larger multinucleate cells, osteoclasts (or bone 
destroyers), among the cells of the marrow cavities, and applied 
to the surfaces of lamellae. These, by dissolving the bone material, 
form the cavities of bone. Note the extent of periosteum over the 
surface of the bone, also portions of muscles attached to this. 


V. THE HUMAN SKELETON 


Materials. —Mounted and disarticulated human skeletons; 
also a variety of skeletons of other mammals, for comparison. 
Note that in the following study, features of bones may usually 
be identified by considering the meaning of the name which they 
bear. Reference books should be used as a help only as a last 
resort. 

A. THE VERTEBRAL COLUMN, RIBS AND STERNUM. 

A general preliminary view of these bones and their relation¬ 
ships should be obtained by arranging upon the table top the 
entire series of vertebrae in their correct order, the thoracic ones 
sufficiently separated from each other to allow the pair of ribs 
corresponding to each to be placed in position beside it, careful 
attention being given to the distinction of rights and lefts. As a 
criterion for the arrangement of the bones, refer to a correctly 
mounted skeleton and apply also the test of fitting together adja¬ 
cent bones by their corresponding articular surfaces. Note the 
gradual transition from each group of vertebrae to the adjacent 
group. 

i. A Typical Thoracic Segment. 

Avoiding the more modified anterior and posterior ends of the 
thoracic region, each student should select for study one of the 
more typical thoracic vertebrae (2nd to 9th inclusive) and its 
corresponding pair of ribs. To understand correctly the relation¬ 
ships of these, the vertebra next anterior to the segment selected 
should be included in the set of bones selected. Record the serial 
number of the segment. 

(a) A Thoracic Vertebra. 

Orientation. —Distinguish dorsal, ventral, anterior, posterior, 
right and left lateral aspects. 

Parts. —Body or centrum; and vertebral arch which encloses, 
dorsal to the body, the vertebral foramen. The arch bears a 

39 


40 


MAMMALIAN ANATOMY 


median dorsal spinous process, two lateral transverse processes, 
two anterior articular processes, and two posterior articular 
processes. 

Note in a lateral view of the two adjacent vertebrae, that the 
anterior vertebral notch of one and the posterior vertebral notch 
of the other form together the intervertebral foramen. 

Articulations. —Note carefully the boundaries of articular 
surfaces. The body articulates with the bodies of adjoining 
vertebrae; the arch articulates with their arches by means of the 
articular processes; each transverse process bears a costal pit 
for the tubercle of the rib, and the body bears costal pits for the 
heads of the rib (tubercular and capitular articulations respec¬ 
tively); note that in the middle thoracic region, the capitular 
articulations are divided between adjoining bodies; note also 
the absence of tubercular articulations in the case of the more 
posterior thoracic vertebras, owing to the reduction of the tuber¬ 
cles of the corresponding ribs. 

(. b ) A Pair of Ribs Corresponding to the Thoracic Vertebra 
Studied. 

Orientation and identification as right or left. 

Parts. —Body, angle, tubercle, neck, head. 

Articulations.- —Tubercle with transverse process of vertebra, 
and head with body of vertebra (or with the two bodies of adja¬ 
cent vertebras); ventrally either directly or indirectly with the 
sternum through the costal cartilage (except the two floating ribs). 

(c) The Sternum. 

Note the division into the manubrium, body, and xiphoid 
process. Identify the articular surfaces for the clavicles, and for 
each pair of ribs. 

To show the relationships of the parts of a typical thoracic seg¬ 
ment, draw either an anterior or posterior view of a thoracic vertebra, 
the corresponding ribs, and a diagrammatic representation of the 
cross section of the sternum, all natural size, the bones slightly sepa¬ 
rated to show their complete form. Draw also a dorsal view of the 
vertebra, a lateral view of the vertebra, together with the adjacent 
anterior one, and a ventral view of the sternum, showing all the rib 
articulations . 


THE HUMAN SKELETON 


41 


2. Comparative Study of Other Regions of the Vertebral 
Column. 

Study these as illustrations of regional differentiation, using 
the parts of the nearest thoracic segment as a basis for interpreting 
the vertebrae of other regions. 

A Typical Cervical Vertebra (3rd to 5th).- —Study as in case of 
the lumbar vertebra; note the presence of the foramina of the 
transverse processes and seek an explanation of their formation 
by comparison with the structure of an anterior thoracic vertebra 
and the ribs articulated with it. Draw an anterior view. 

The Atlas and Epistropheus. —Study these carefully for 
specializations due to their function of supporting the skull; note 
in the atlas the absence of the body, and the consequent ring-like 
form of the bone, with dorsal and ventral arches, the latter forming 
an articulation with the tooth of the epistropheus; peculiarities 
in shape and position of articular surfaces (a) on the atlas for 
articulation with the occipital condyles of the skull, (b) on both 
atlas and epistropheus for articulation with each other; note the 
direction and extent of the motion of the head made possible by 
these articulations, and compare this with the range of movement 
of other parts of the vertebral column. Draw an anterior view 
of atlas , also a lateral view of both atlas and epistropheus , the bones 
slightly separated to show their complete shape. 

A Typical Lumbar Vertebra. —Note the peculiarities in form 
and size of body, arch, and processes. Compare with the various 
thoracic vertebrae as to the slant of processes and the number and 
position of articular surfaces. Draw an anterior view. 

The Sacrum. —Note the number and relation of fused com¬ 
ponent parts, and find a reason for the fusion; lateral masses 
formed by the fused ribs; the continuation of the vertebral canal; 
foramina in three series, intervertebral, dorsal, and ventral, and 
their relation to the component sacral vertebrae and rib elements; 
auricular surfaces for the attachment of the pelvic girdle. Draw a 
dorsal or a ventral view. 

The Coccyx. —Note the number of component parts and the 
extent to which these are fused (cf. with parts of a typical vertebra 
and with the caudal vertebrae of other mammals). Add the 
coccyx to the drawing of the sacrum. 


42 


MAMMALIAN ANATOMY 


B. THE SKULL. 

i. Shape and General Proportions. 

In this study compare as many examples of human skulls as are 
available and note the extent of individual variation. Some of 
these should be skulls which have been sawn horizontally through 
the walls of the cranial cavity. Determine each aspect studied 
with great exactness, using as the horizontal plane of reference, the 
plane passing through the lower margin of the orbits and the upper 
margin of the external acoustic meatus. This plane is known as 
the “ Frankfort horizontal.” 

Lateral View. —Distinguish cranial and facial regions; deter¬ 
mine and compare facial angles of different species of mammals 
and different individuals of the same species, noting degree of 
prognathism and human tendency in the direction of orthogna¬ 
thism; note extreme reduction of the jaws in certain individu¬ 
als (cf. variation in this respect shown by Boston bull dogs and 
grayhounds); note effect of orthognathism upon the teeth as 
shown in the reduction of the dental arcade with crowding and 
atrophy of the posterior molars. 

Basal View. —Note the position of the occipital foramen, 
compare with other mammals, and explain the difference. 

Vertical View. —Compare relative amounts of facial and 
cranial regions visible in this view of the skulls of different mam¬ 
mals; note individual and racial variations in the proportions of 
the human skull (“long” and “short” heads). 

Frontal View. —Note direction of axes of orbits; compare 
man with other mammals with regard to extent of field of vision 
and range of binocular vision; note correlation of small size of 
nasal region with large eye and brain development and with 
orthognathism. 

Record the observations made by blocking out, in very light lines, 
outline drawings, natural size, of lateral, basal, vertical, and frontal 
views of the skull, and internal views of the floor and roof of the 
cranial cavity. As the study of the special features is taken up, 
record each of these, with care as to details of relationships, upon 
each view in which it is visible. Finally finish up each drawing 
with the usual clear cut outlines. 


THE HUMAN SKELETON 


43 


2. Special Features. 

(a) External. 

Ridges, Processes, etc. —Superciliary arches, zygomatic arches, 
postorbital bars, temporal ridges, external occipital protuberance 
and crest (cf. lambdoidal ridge in those mammalian skulls in 
which the temporal ridges meet), alveolar ridges of upper and 
lower jaws, and the types of teeth which they bear (cf. human 
dentition with that of other mammals), pterygoid processes and 
hamuli, styloid processes, mastoid processes, occipital condyles; 
on the lower jaw note also the coronoid processes, the condyloid 
processes, the angles of the jaw, and the mental protuberance. 

Fossae. —Orbital, temporal, nasal, and mandibular (for articu¬ 
lation with lower jaw). 

Foramina, Fissures, etc. —Supraorbital, infraorbital, and 
mental foramina, for the exit of the terminal portions of the three 
branches of the trigeminal nerve; mandibular foramen for the 
entrance into the mandibular canal of the third branch of the 
trigeminal nerve; piriform opening (anterior nares), choanae 
(posterior nares), larger and smaller palatine foramina; lacrimal 
foramen; optic foramen, superior orbital fissure, inferior orbital 
fissure, foramen rotundum, foramen ovale, lacerated foramen, 
semicanal of auditory tube (Eustachian tube), carotid canal, 
jugular foramen, hypoglossal canal, condyloid canal, occipital 
foramen; external acoustic meatus, stylomastoid foramen, mas¬ 
toid foramen (or foramina). All of these are paired except the 
occipital foramen. 

( b ) Internal (within cranial cavity). 

Use for this purpose a horizontally sawn skull. Note the 
structure of the bones of the cranium as shown by the cut edges. 

In the roof of the cranial cavity note the grooves for the veins 
and arteries, and granular foveolae. 

In the floor of the cranial cavity note: 

Ridges and Processes. —Crista galli, clinoid processes, and 
prominent ridges separating anterior, middle, and posterior 
cranial fossae. 

Fossae. —Anterior cranial, middle cranial, posterior cranial; 
sella turcica; grooves for veins and arteries. 


i 



44 


MAMMALIAN ANATOMY 


Foramina. —Numerous perforations in the cribriform plate 
of the ethmoid for the olfactory nerves; optic foramen for the 
optic nerve; superior orbital fissure for motor nerves to the eyeball 
muscles (oculomotor, trochlear, and abducent), and for the first 
branch of the trigeminal; foramen rotundum for the second 
branch of the trigeminal; foramen ovale for the third branch of 
the trigeminal; internal acoustic meatus for the facial and acous¬ 
tic nerves; jugular foramen for the glossopharyngeal, vagus, and 
spinal accessory nerves; hypoglossal canal for the hypoglossal 
nerve. (Cf. demonstration preparation of the human skull 
showing the course of the cranial nerves.) 

4. Bones of the Skull. 

Identify, by means of disarticulated skulls, the extent and 
boundaries of the individual bones, and add these outlines to all of 
the drawings in so far as they are visible , showing particularly the 
relation of the individual bones to the various features of the skull. 
In the final finishing up of the drawings , leave the outlines of the 
bones in lighter lines that they may not be confounded with the 
features of the skull as a whole. 

(a) Cranium. 

Frontal—1. 

Parietals—2. 

Occipital—1. 

Temporals—2. 

Auditory ossicles—3 pairs (Cf. demonstration preparations.) 
Ethmoid—1. 

Sphenoid—1 (In adult fused with occipital.) 

(b) Face. 

Nasals—2. 

Maxillaries—2. 

Zygomatics—2. 

Palatines—2. 

Inferior turbinated—2. 

Lacrimals— 2. 

Vomer—1. 

Mandible—1. 



THE HUMAN SKELETON 


45 


Hyoid bone—i. (A complex of several bones and cartilages, 
in man suspended by ligaments from the styloid processes, 
and not present in the usual dry preparations of the skele¬ 
ton. Cf. demonstration dissection of tongue and larynx.) 

C. THE APPENDICULAR SKELETON. 

Study both articulated and disarticulated skeletons of the 
girdles and the appendages; learn in each case to orient completely 
the bone in question, and to give definite reasons for your orienta¬ 
tion in exact scientific language; work out the relation of adjoining 
bones to each other as indicated by the articular surfaces where 
they come in contact. 

Draw at least one view of each bone, preferably, in the case of 
the free limb, the same aspect (extensor or flexor) of all the bones of 
the limb, so placed as to show their relation to each other but suffi¬ 
ciently separated to show the entire outline of each bone. In case a 
bone is drawn separately, include in the drawing the corresponding 
articular region of adjoining bones. 

i. The Anterior Appendage. 

(a) The Pectoral Girdle. 

Scapula. —Note triangular shape; costal (ventral) and dorsal 
surfaces; three margins,* anterior, axillary, and vertebral; spine 
ending in the acromion with the articular surface for the clavicle; 
coracoid process; scapular notch; supraspinous and infraspinous 
fossae; subscapular fossa; head, with glenoid cavity for articula¬ 
tion with the humerus; neck. 

Clavicle. —Note double curve; the rounded sternal extremity 
and its articular surface, and the flattened acromial extremity and 
its articular surface; the smooth anterior (superior) surface and 
the roughened posterior (inferior) one; the coracoid tuberosity. 

(b) The Free Limb. 

Humerus. —Head (articular surface for the scapula); anatomi¬ 
cal neck; surgical neck; larger and smaller tubercles, with a 
groove for the tendon of biceps (the intertubercular sulcus) lying 
between; deltoid tuberosity; medial and lateral epicondyles, with 
ridges extending from these up the shaft; trochlea, the articular 
surface for the ulna; capitulum, the articular surface for the 


46 


MAMMALIAN ANATOMY 


radius; groove for the ulna nerve; coronoid fossa; olecranon fossa 
(this may pierce the bone and open into the coronoid fossa thus 
forming the supratrochlear foramen). 

Ulna. —Olecranon; coronoid process; semilunar notch for the 
trochlea of humerus; radial notch for head of radius; interosseous 
crest; head (at distal end), with styloid process and articular 
surface for the radius. 

Radius. —Head with pit (fovea) for articulation with the 
capitulum of the humerus; articular circumference for the radial 
notch of the ulna; tuberosity for the insertion of the biceps muscle; 
interosseous crest; distal end with styloid process, ulnar notch, 
and articular surfaces for the naviculare and lunatum. 

Carpus. —Proximal row consisting of the navicular, lunate, 
triquetral, and pisiform bones; distal row consisting of the greater 
and lesser multangular, the capitate, and the hamate bones. 
Note how the bones of this row are associated with the separate 
digits. 

Hand. —Note the five digits with similar bones arranged in 
successive ranks, the proximal rank consisting of metacarpals, 
the remaining ranks of phalanges. Determine the number of 
these in each digit. Note the characteristics by which phalanges 
are distinguished from metacarpals, and proximal, middle, and 
distal phalanges from each other. Loo*k for indications in the 
form of the articulations, of greater mobility of the thumb than 
of the other digits. 

* i 

2. The Posterior Appendage. 

(a) The Pelvic Girdle. 

Ossa Coxae. —Note that each of these is made up of three 
components which fuse into one bone, the os coxae, at about the 
13th or 14th year. The three components meet in the center of a 
deep cup, the acetabulum, in the formation of which they partake 
about equally. Note the linea terminalis which, when the two 
ossa coxae and the sacrum are fitted together, forms the boundary 
line between the upper and lower pelvic cavities. 

The os ilium is the broad shovel-like region which projects 
anteriorly and laterally and articulates with the sacrum. Note 
the lateral and medial surfaces; the iliac fossa of the later; the 


THE HUMAN SKELETON 


47 


crest, and the two ventral, and two dorsal spines; posterior to 
the latter the greater sciatic notch, in the middle of which the 
ilium joins the ischium; the auricular surface on the medial surface 
of the bone for the articulation with the sacrum. 

The os ischii is the most posterior component, having the 
form of a loop. Note the sciatic tuber, which supports the weight 
of the body in sitting; the sciatic spine, separating the greater 
from the lesser sciatic notch; the ramus, meeting the ramus of the 
pubis and bounding the obturator foramen. 

The os pubis is the most ventrally situated component. Note 
the body forming, with the corresponding portion of the other 
side, the pubic arch; the symphyseal surface along which it comes 
in contact with the pubic bone of the other side, in the midventral 
line; the ramus, meeting the ramus of the ischium. 

Sex Differences Shown by the Pelvic Girdle. —These are best 
seen when the two ossa coxae and the corresponding sacrum are 
fitted together and held firmly in place. Compare as large a 
number of examples as possible as to the subpubic angle formed by 
the posterior margins of the pubic rami, narrow (averaging 58°) 
in the male, wide (averaging 76°) in the female; shape of the iliac 
fossa, obturator foramen, sacro-sciatic notch, and sciatic tubers; 
the presence or absence of a preauricular fossa, which most females 
possess; and the shape and size of the ring formed by the sacrum 
and the ossa coxae. In correctly mounted male and female 
skeletons note the difference in the inclination of the pelvis as a 
whole to the axis of the trunk. (Cf. the pelvic girdle with that of 
quadrupedal forms in this particular and in general proportions.) 

(, b ) The Free Limb. 

Femur (the longest bone of the body, the entire height = 
3.7 X length of femur). —Note head with its surface for articu¬ 
lation with the acetabulum; pit (fovea) in the middle of the head 
for the ligamentum teres which holds the femur in the acetabulum; 
anatomical neck (coincides with the surgical neck); note variation 
of the angle between the neck and the shaft at different ages, with 
nearer approach to a right angle and consequent liability to 
fracture in old age; greater and lesser trochanters connected by 
intertrochanteric lines; trochanteric fossa; linea aspera; popliteal 


48 


MAMMALIAN ANATOMY 


plane; lateral and medial condyles, with articular surfaces for 
the tibia; lateral and medial epicondyles; intercondyloid fossa; 
articular surface for the patella. 

Tibia. —Note lateral and medial condyles with superior articu¬ 
lar surfaces for the condyles of the femur; dorsal and ventral 
intercondyloid fossae; intercondyloid eminence; articular surface 
for proximal end of the fibula; tuberosity; anterior crest; inter¬ 
osseous crest; medial malleolus; inferior and malleolar articular 
surfaces for the talus; fibular notch for the distal articulation of 
the fibula. 

Fibula. —Note head; apex of head; interosseous crest; lateral 
malleolus; proximal and distal articular surfaces for the tibia, 
articular surface of the malleolus. 

Patella (a sesamoid bone). —Note apex, base, and articular 
surface for femur. 

Tarsus. —Proximal row, consisting of calcaneus and talus; the 
navicular bone, interposed between the talus and the distal row; 
the distal row, consisting of the first (medial), second, and third 
cuneiform bones, and the cuboid bone. Note that the surfaces for 
articulation with the tibia and fibula are located upon the talus, 
which also articulates with the calcaneus, the shelf-like process of 
which (sustentaculum tali) supports the talus from below. Work 
out with care the other intertarsal articulations, and the relation of 
the bones of the distal row to the separate metatarsals (cf. cor¬ 
responding bones of hand). 

Foot. —Note the five digits with ranks of bones as in the case of 
the hand, metatarsals forming the first rank and phalanges the 
remaining ones. Note prominent process on the fifth metatarsal. 
Look for indications, in the forms of the articular surfaces, of less 
movability of the great toe than of the thumb. Note frequency of 
fusion of middle and distal phalanges of the little toe, a general 
human tendency found as often in barefooted races as in those 
wearing shoes, and hence not due, as often asserted, to the latter 
condition. 

D. SUGGESTED SUPPLEMENTARY EXERCISES. 

i. Identification and classification of the articulations, or 
arthroses, immovable (synarthroses), slightly movable (amphi- 


/ 



THE HUMAN SKELETON 49 

arthroses), and freely movable (diarthroses), with the various 
'forms of each, particularly the latter group. (Cf. demonstration 
preparations of articulations, showing arrangement of ligaments.) 
Record the study of arthroses by appropriate labeling of the drawings 
already made. 

2. Practice in identifying fragments of human bones which 
bear distinctive features, also whole bones and fragments of bones 
of other mammals, in which the features are for the most part 
sufficiently like those of the human bones to be recognizable. 


4 


VI. HISTOLOGY OF MUSCLE TISSUE 


A. SMOOTH OR UNSTRIATED INVOLUNTARY MUSCLE. 

1. Tease on a slide a few shreds from a portion of the muscular 
coat of the intestine of a cat or other mammal (fresh material), 
which has macerated for 48 hours in 20% nitric acid. Add 
glycerine and cover. Study the preparation with the compound 
microscope, and note that each muscle fiber consists of a single 
elongated, spindle-shaped cell with one granular, elongated nucleus, 

. and with numerous fibrils extending lengthwise through the cyto¬ 
plasm. Draw a jew well-selected examples. 

2. Study transverse sections (Lab. SI. Coll.) through the small 
intestine of Necturus or other amphibian. Note that the mus¬ 
cular coats, both circular and longitudinal, are composed of smooth 
muscle cells closely packed together with their long axes parallel 
to each other. Draw a detail showing a longitudinal section of a 
few adjacent cells (from the circular coat), and one showing a jew 
cells in cross section (from the longitudinal coat). 

B. STRIATED VOLUNTARY MUSCLE. 

From your study of all the following preparations note that a 
striated or voluntary muscle fiber consists of a long, cylindrical, 
multinucleate structure, or syncytium, enclosed in a delicate 
membrane, the sarcolemma, and ending at each end in the case of 
vertebrates in a conical attachment to a bundle of tendon fibers. 
Within the sarcolemma and visible only with high power, are 
innumerable minute fibrils, extending throughout the entire 
length of the fiber and exhibiting minute cross striations. These 
are the contractile elements of the liber, and their cross striations, 
visible en masse even under low power, give the fiber as a whole its 
cross-striated appearance. Note whether nuclei are scattered 
throughout the thickness of each fiber or lie only immediately 
beneath the sarcolemma (cf. rabbit and Necturus in this regard). 

1. Tease in a drop of normal salt solution on a slide, a few 
shreds of voluntary muscle from a recently killed animal, for 

50 


HISTOLOGY OF MUSCLE TISSUE 


51 


example, Necturus, frog, or rat. Cover and examine. Stain 
under the cover-slip with methylene blue. 

2. Mount in a drop of glycerine a few teased fibers of muscle, 
either amphibian or mammalian, which has been preserved in 
70% alcohol or 10% formalin. Cover and examine. 

3. Study transverse and longitudinal sections of rabbit and of 
Necturus muscle (Lab. SI. Coll.). 

Draw details to show your conception of the structure of a striated 
muscle fiber, including cross sections of fibers. 

C. STRIATED INVOLUNTARY, OR HEART MUSCLE. 

Examine sections of heart muscle and note that although its 
fibrils show cross striations very similar to those of voluntary 
muscle, the syncytium is in the form of a reticulum instead of 
separate fibers, and that the nuclei are relatively large and few. 
Draw. 


VH. DETAILED ANATOMY OF LIMB MUSCLES 

f 

Material. —Full-grown rabbit (or cat). This should be pre¬ 
pared several days, at least, before it is to be used, by the following 
method: Remove the skin from the entire animal except the feet, 
and the region immediately surrounding the orifices. Evis¬ 
cerate the abdomen through a transverse incision. (For con¬ 
venience in hardening, this transverse incision may be extended 
to divide the whole body into anterior and posterior halves.) 

Harden in a considerable quantity of saturate solution of 
corrosive sublimate (bichloride of mercury) for 3 days. Wash 
thoroughly with water. Preserve for subsequent work in 60% 
alcohol. 

Directions for Dissection. —In dissecting muscles, always 
expose each muscle by removing loose connective tissue coverings 
and attachments to other muscles, but leave intact as long as 
possible the muscle itself and its tendinous attachments. Study 
each muscle in its relationship to others and to the bony skeleton, 
using for reference, rough skeletal preparations 1 of the part 
studied. Note its form, the direction of its fibers, its origin and 
insertion, and reason out from this what its work must be. Iden¬ 
tify each muscle by its origin and insertion using the tabulated 
list 2 as a means for naming the muscles of a region after these have 
been dissected and studied, since often the complete identification 
must be postponed until other muscles have been worked out. 
When it is necessary to cut a muscle, make a clean cut transversely 
through the belly and reflect each end in order to follow out the 
muscle completely and to expose underlying parts. Never remove 
a muscle until it has been fully studied and drawn, and then only 
when necessary to expose deeper parts. 

Make a series of carefully labeled drawings to show all the facts 
determined. 

Finally skeletonize the appendage and girdle which you have 
dissected, by cutting off each muscle from its two attachments 

1 The supply of these skeletal preparations is provided for and kept up from year 
to year by means of those which each class makes upon the completion of this piece 
of dissection. 

2 In case the cat is used instead of the rabbit, Davidson’s Mammalian Anatomy 
with Especial Reference to the Cat will be found helpful. 

52 


DETAILED ANATOMY OF LIMB MUSCLES 


53 


to the bones, leaving the bones themselves held together by 
ligaments. 

Before discarding the material remove the kidneys and pre¬ 
serve them in 70% alcohol for later study, p. 132. 


A. THE ANTERIOR LIMB MUSCLES. 

Superficial muscles of the shoulder and chest region 

(Identify the dorsolumbar fascia which covers all but the most superficial muscles of the 
back, and is continuous anteriorly with the cervical fascia.) 


Name of muscle 

Origin 

Insertion 

1. Trapezius. 

From the dorsolumbar fas¬ 
cia, and along the mid¬ 
dorsal line over the spinous 
processes of the thoracic 
and cervical vertebrae, and 
from the occipital protuber¬ 
ance of the skull. 

Metacromion process, supra¬ 
scapular fascia, and dorsal 
half of spine of scapula. 

2. Latissimus dorsi. 

Partly from the dorsolumbar 
fascia, partly from the three 
posterior ribs. 

Medial surface of shaft of 
humerus. 

3. Levator scapulae. 

Base of the skull. 

Metacromion process. 

4. Sternomastoideus. 

Anterior end of sternum. 

Mastoid process of skull. 

5. Cleidomastoideus 

Clavicle. 

Mastoid process of skull. 

6. Occipitohumeralis. 

Base of the skull. 

Lateral third of clavicle. 

7. Cleidodeltoideus. 

Lateral half of clavicle. 

Deltoid tuberosity of hum¬ 
erus. 

8. Acromiodeltoideus. 

Acromion process of scapula. 

Deltoid tuberosity of hum¬ 
erus. 

9- Spinodeltoideus. (More con¬ 
veniently studied in con¬ 
nection with the muscles 
of the scapula.) 

Infraspinous fascia, the spine 
of the scapula, acromion 
and metacromion. 

Lateral surface of humerus 
distal to its head. 

10. Pectoralis major, consisting 
of many divisions. 

Sternum. 

Deltoid tuberosity (ridge) 
of humerus. 

Deeper muscles of the shoulder and chest region 

11. Pectoralis minor. 

Sternum. 

Clavicle and supraspinous 
fascia. 

12. Rhomboideus major. 

Spines of anterior thoracic 
vertebrae. 

Vertebral border of scapula. 

13. Rhomboideus minor. 

Spines of cervical vertebrae. 

Vertebral border of scapula. 

14. Rhomboideus capitis. 

Lateral surface of the skull 
posterior to the ear. 

Vertebral border of scapula. 

15. Serratus anterior. 

By digitations from the 
lateral region of the third 
to ninth ribs. 

Vertebral border of scapula. 

16. Levator anguli scapulae. 

Transverse processes of pos¬ 
terior five cervical ver¬ 
tebrae. 

Costal surface of scapula 
close to its vertebral border. 

Muscles on the costal surface of the scapula 

17. Teres major. 

Axillary border of scapula 

Shaft of humerus near 
insertion of the latissimus 
dorsi. 


















































































54 


MAMMALIAN ANATOMY 


Name of muscle 

Origin 

Insertion 

1 8. Subscapularis. 

Whole surface of the sub- 

Smaller tubercle of humerus. 


scapular fossa. 

19. Coracobrachialis. 

Coracoid process of scapula. 

Proximal end of shaft of 


humerus. 


Muscles of the outer surface of the scapula 


20. Supraspinatus, covered by 
the pectoralis minor (11). 

Whole surface of supraspin¬ 
ous fossa. 

Proximal margin of larger 
tubercle, of humerus. 

21. Infraspinatus, covered by the 
spinodeltoideus (9). 

Whole surface of infraspin- 
ous fossa. 

Larger tubercle of humerus. 

22. Teres minor. 

Ventral third of axillary 
border of scapula. 

Larger tubercle of humerus. 



Muscles of the upper arm 


23. Extensor parvus antibrachii... 

Fascia of the upper arm. 

Olecranon. 

24. Triceps brachii, of four parts 
of heads: 



(a) Long head. 

Ventral third of axillary 
border of the scapula. 

Olecranon. 

C b ) Lateral head. 

Lateral surface of the shaft 
of the humerus and lateral 
epicondyle. 

Olecranon. 

( c) Medial head. 

Medial surface of the shaft 
of the humerus. 

Olecranon. 

( d) Accessory head. 

Medial epicondyle of hu¬ 
merus. 

Olecranon. 

25. Biceps brachii. 

Anterior edge of glenoid 
cavity (tendon of origin 
runs through the inter- 
tubercular sulcus). 

Tuberosity of radius. 

26. Brachialis. .,. 

Lateral surface of proximal 
portion of humerus. 

Radius proximal to insertion 
of biceps. 


Muscles of the forearm and hand, extensor group 


27. Extensor carpi radialis. 

Lateral epicondyle of hu¬ 
merus. 

Proximal ends of second 
and third metacarpals. 

28. Extensor digitorum com¬ 
munis. 

Lateral epicondyle of hu¬ 
merus. 

Tendons pass under the 
annular ligament and are 
inserted into the middle and 
distal phalanges of the second 
to the fifth digits. 

29. Extensor pollicis et indicis.... 

Proximal region of shafts of 
ulna and radius. 

• 

Tendon enters the hand with 
that of extensor digitorum 
communis (28), divides into 
two, one of which is inserted 
into distal phalanx of pol- 
lex, the other £into distal 
end of metacarpal of index. 

30. Abductor pollicis. 

Lateral surface of shaft of 
radius. 

Metacarpal of pollex. 

31. Extensor quarti digiti, exten¬ 
sor quinti digiti, extensor 
carpi ulnaris. 

Three slender muscles arising 
close together from lateral 
epicondyle of humerus (the 
extensor quinti digiti also in 
part from the shaft of the 
ulna). 

Distal phalanx of fourth 
digit, fifth metacarpal and 
proximal phalanx of the 
fifth digit, and proximal end 
of fifth metacarpal, respec¬ 
tively. 








































































DETAILED ANATOMY OF LIMB MUSCLES 


55 


Muscles of the forearm and hand, flexor group 


Name of muscle 

Origin 

Insertion 

32. Flexor carpi ulnaris. 

Medial face of olecranon and 
medial epicondyle of hu¬ 
merus. 

Pisiform. 

33. Pronator teres. 

Medial epicondyle of hu¬ 
merus. 

Middle of medial side of 
shaft of radius. 

34. Flexor carpi radialis. 

Medial epicondyle of hu¬ 
merus, adjacent to origin of 
pronator teres (33). 

Proximal end of second 
metacarpal. 

35 - Palmaris. 

Medial epicondyle of hu¬ 
merus in association with 
the superficial head of the 
flexor digitorum profundus 
( 37 ). 

Lost in palmar fascia, or 
sheet of connective tissue 
covering ventral surface of 
manus, sending off a small 
slip which is inserted into 
distal phalanx of pollex. 

36. Flexor digitorum sublimis 
(perforatus). 

Medial epicondyle of hu¬ 
merus between the flexor 
carpi ulnaris and the super¬ 
ficial head of the flexor 
digitorum profundus (37). 

Divides into four tendons 
which are superficial to the 
tendon of flexor digitorum 
profundus, and pass to the 
manus and ventral faces of 
the second to fifth digits, 
where each tendon divides 
at base of proximal phalanx 
into two slips which pass 
one on either side of 
phalanx to be inserted into 
proximal end of middle 
phalanx. 

37. Flexor digitorum profundus 
(perforans) made up by 
union of four heads: 

(a) Superficial head. 

Medial epicondyle of hu¬ 
merus. 

Its tendon spreads out into 
a broad stout sheath lying 
immediately dorsal to the 
tendon of the flexor digi¬ 
torum sublimis (36); from 
this sheath five tendons are 
given off, one to each digit, 
each passing along the 
ventral face of the digit to be 
inserted into its distal 
phalanx; in the second to 
fifth digits the tendons pass 
between the two slips into 
which the corresponding 
tendon of the flexor digi¬ 
torum sublimis is divided. 

( b) Middle head. 

Medial epicondyle of hu¬ 
merus. 

(c) Radial head. 

Proximal part of flexor sur¬ 
face of the radius. 

(d) Ulnar head. 

Flexor surface of ulna. 


B. THE POSTERIOR LIMB MUSCLES. 

Muscles of the lumbar region 

(The muscles of this group lie in the dorsal wall of the abdominal cavity and for the most 
part pass beneath the inguinal ligament to reach their insertion into the appendicular skeleton. 
This ligament, which stretches from the anterior spine of the crest of the ilium to the tubercle 
of the pubis, serves not only as the insertion of portions of the abdominal muscles but also as the 
origin of the sartorius muscle (14), and it is therefore advisable to postpone the dissection 
and identification of the lumbar group of appendicular muscles until after the muscles of the 
medial surface of the thigh have been studied.) 








































56 


MAMMALIAN ANATOMY 


Name of muscle 

Origin 

Insertion 

i. Psoas major. 

Last three ribs, the ventral 
surface of the bodies of the 
last three thoracic and all 
the lumbar vertebrae. 

Into the lesser trochanter of 
the femur. 


2. Quadratus lumborum. 

Two parts separated by 
transverse processes of lum¬ 
bar vertebrae; the inner 
arising from last five thor¬ 
acic and all the lumbar 
vertebrae, the outer from 
last five ribs, and corre¬ 
sponding transverse pro¬ 
cesses, and from all the 
lumbar vertebrae. 

Partly into the lumbar 
vertebrae partly into ventral 
border of os ilium. 


3. Psoas minor. 

Ventral surface of the bodies 
of the four posterior lum¬ 
bar vertebrae. 

Pubis by a tendon which 
acquires a connection with 
inguinal ligament. 


4. Iliacus, continuous with the 
inner part of quadratus 
lumborum (2). 

Ventral faces of last lumbar 
and first sacral vertebrae, 
and medial and lateral sur¬ 
faces of the os ilium. 

Lesser trochanter of the 
femur. 


Superficial muscles of the hip and thigh regions, lateral and flexor surfaces 

(The fascia lata which covers over the muscles of this region serves as the origin of some of 
the more superficial portions of these muscles. It should not be removed but may be slit 
along the lines of the boundaries of the muscles which lie beneath.) 


5. Biceps femoris: 

(a) Anterior head. 

Sacral and three anterior 
caudal vertebrae. 

Into the lateral border of a 
strong and extensive fasci a 
over distal end of femur 
and proximal end of tibia . 


( b) Posterior head: 

Main portion. 

Posterior part of sciatic 
tuber. 

Anterior part of sciatic tuber. 

Accessory portion... . 

6. Semimembranosus. 

Sciatic tuber. 

By same fascia as gracilis (15) 
into proximal part of the 
medial border of tibia; 
from the distal end of its 
posterior edge a long tendon 
passes along the medial side 
of the lower leg and joins 
the tendon of the triceps 
surae (25). 


7. Glutaeus maximus. 

Sacrum, dorsal border of the 
os ilium, and fascia lata; 
dorsally its origin is cov¬ 
ered by the anterior head 
of the biceps femoris (50) 
ventrally it blends with 
the rectus femoris (21a). 

Slightly distal to the greater 
trochanter of the femur, 
into the third trochanter. 



Deeper muscles of the hip region 


8. Glutaeus medius, covered by 
glutaeus maximus (7). 

Dorsal border of os ilium 
and from sacrum. 

Greater trochanter of femur. 

9. Glutaeus minimus, covered by 
the glutaeus medius (8). 

Dorsal border and lateral 
surface of the os ilium, and 
from the first sacral ver¬ 
tebrae. 

Greater trochanter of femur. 

10. Piriformis. 

Second and third sacral 

Greater trochanter beneath 
the insertion of the glutaeus 
medius, and posterior and 
dorsal to that of the glutaeus 
minimus. 


vertebrae. 


















































DETAILED ANATOMY OF LIMB MUSCLES 


57 


Name of muscle 

Origin 

Insertion 

ii. Quadratus femoris. 

Sciatic tuber. 

Extensor side of shaft of 
femur, slightly distal to the 
level of the greater tro¬ 
chanter. 

12. Obturator internus, and the 
two gemelli. 

Medial aspect of membrane 
which covers the obturator 
foramen, and from the 
medial surface of the pubis 
and ischium. 

Trochanteric fossa. 

13. Obturator externus. 

Lateral aspect of the obtura¬ 
tor membrane. 

Trochanteric fossa. 

Muscles of the medial surface of the thigh 

14. Sartorius. 

Middle of inguinal ligament. 

Blends with the anterior edge 
of the gracilis (15). 

15. Gracilis. 

Whole length of symphysis 
pubis. 

By a broad fascia which 
inserts into the proxima 
part of the medial border of 
the tibia. 

16. Adductor magnus. 

Posterior edge of ischium 
and sciatic tuber. 

Medial edge of distal end of 
femur and medial condyle 
of tibia. 

17. Semitendinosus, imbedded in 
the adductor magnus (16). 

Sciatic tuber. 

By a long tendon which 
emerges from the adductor 
magnus (16), near the 
distal end of its outer sur¬ 
face, and is inserted into the 
medial condyle of the tibia. 

18. Adductor longus. 

Whole length of symphysis 
pubis. 

Middle third of shaft of 
femur. 

19. Adductor brevis. 

Anterior end of symphysis 
pubis. < 

Shaft of femur. 

20. Pectineus. 

Pubic arch. 

Shaft of femur. 

1 

Muscles of the extensor surface of thigh 

21. O ua driceps femoris, consist¬ 
ing of the following parts: 

(a) Superficial head of rec¬ 
tus femoris. 

t 

Ventral border of the os 
ilium. 

By a strong thick tendon, 
the ligamentum patellae (in 
which the patella is em¬ 
bedded), into the crest of 
the tibia. 

(6) Deep (short head of 
rectus femoris partly 
enwrapped by vastus 
lateralis. 

Posterior part of ventral 
border of os ilium. 

(c) Vastus medialis. 

Neck of the femur. 

(d) Principal (superficial 
head of vastus lateralis 

Neck of femur and greater 
trochanter. 

( e ) Accessory (deep) head 
of vastus lateralis. 

Femur close to origin of 
superficial head. 

(/) Vastus intermedius. 

Shaft of femur. 

Muscles of the lower leg and foot 

22. Tibialis anterior. 

Lateral condyle and anterior 
crest of the tibia. 

Proximal end of second 
(apparent first) metatarsal. 

















































































58 


MAMMALIAN ANATOMY 


Name of muscle 

Origin 

Insertion 

23. Extensor digitorum com¬ 
munis. 

Anterior surface of the distal 
end of the femur, external 
to the anterior intercondy- 
loid fossa, the tendon of 
origin passing through the 
capsule of the knee joint. 

Distally the muscle divides 
into four tendons which 
pass under the annular 
ligament, and are inserted 
into the middle and distal 
phalanges of the four digits. 

24. Extensor digiti secondi. 

Medial surface of proximal 
end of tibia. 

Unites with the first tendon 
of the extensor digitorum 
communis (23). 

25. Triceps surae, consisting of: 
(a) Gastrocnemius, a large 
two headed muscle 
forming the larger part 
of the calf of the leg. 

1. Medial head..*.... 

Medial epicondyle of femur 
and medial sesamoid of 
knee joint. 

The two parts of the gastro¬ 
cnemius and the soleus unite 
to form a large strong ten¬ 
don, the tendo calcaneus 
(of Achilles), which is in¬ 
serted into the extremity of 
the tuber of the calcaneum. 

2. Lateral head. 

Lateral epicondyle of femur 
and lateral sesamoid of 
knee joint. 

(b) Soleus. 

Head of fibula. 

26. Plantaris ( = flexor digitorum 
sublimis of hand) en¬ 
wrapped by the gastrocne¬ 
mius (25a). 

Posterior surface of the 
femur proximal to the 
lateral epicondyle, and from 
the lateral sesamoid of the 
knee joint. 

Its tendon divides into four 
slips, each of which divides 
at the base of the proximal 
phalanx into two slips, 
which pass on either side of 
the phalanx, and are in¬ 
serted into the proximal end 
of the middle phalanx. 

27. Popiiteus. 

Lateral epicondyle of femur. 

Proximal region of posterior 
surface of the tibia. 

28. Flexor digitorum communis 
(= flexor digitorum pro¬ 
fundus of the hand). 

Head of fibula and posterior 
surface of proximal region 
of both fibula and tibia. 

Four tendinous slips, each of 
which passes between the 
two slips into which each 
tendon of the plantaris (26) 
divides, and is inserted into 
the terminal phalanx of the 
digit. 

29. Peroneus longus. 

Lateral condyle of tibia. 

Cuboid. 

30. Peroneus brevis. 

Lateral condyle of tibia. 

Proximal end of fifth (last) 
metatarsal. 

31. Peroneus quarti digiti. 

Shaft of fibula. 

Distal end of fourth (ap¬ 
parent third) metatarsal. 

32. Peroneus quinti digiti. 

Lateral condyle of tibia and 
head of fibula. 

Distal end of fifth (last) 
metatarsal. 


















































VIII. HISTOLOGY OF NERVE TISSUES 


A. NERVE CELLS (NEURONES). 

i. Smear preparations of gray nerve substance from the spina 
cord. These are made by applying to a clean cover-slip by means 
of the point of a scalpel, a bit of the gray matter from the freshly 
exposed ventral region of the spinal cord of a recently killed 
mammal . 1 Remove the cover-slip with the adhering nerve sub¬ 
stance, place this in contact with another cover-slip, press the two 
tightly together and then separate them by sliding them apart, 
thereby spreading the nerve substance in a thin film over the 
surface of each glass. Dry these smears by holding each carefully 
in a pair of forceps and passing it three or four times, film side up, 
through an alcohol flame, allowing a few seconds to elapse between 
each two successive exposures to the flame. When the film is dry, 
stain it in a dilute aqueous solution of methylene blue by gently 
floating the cover-slip, film down, upon the surface of the stain, 
which may be conveniently used in a watch glass. The process 
of staining should be continued until a deep purple color is 
imparted to the film. Rinse in water, dry off the excess of water 
with filter paper, being careful not to touch the film, and lay the 
preparations aside with the film up until thoroughly dry. Clear 
by floating each cover-slip, film down, in a watch crystal of xylol. 
Place a drop of balsam on the middle of a clean slide and after 
carefully removing the excess of xylol from the film, place the 
cover-slip, film down, upon the balsam. 

Examine under low power, and amid the general debris look 
for large, branched nerve cells. Move the slide so as to bring one 
of these into the center of the field and apply the high power. 
Note the nucleated cell body or perikaryon; the numerous deeply 
stained tigroid bodies (Nissl corpuscles) and delicate neuro-fibrillse 
in the cytoplasm; the paler nucleus, often irregular in outline 

1 Material obtained from a market often proves excellent, even after it has 
been frozen. 


59 


6o 


MAMMALIAN ANATOMY 


surrounded by a clear circumnuclear zone, and containing always a 
deeply stained nucleolus. Examine the various cytoplasmic 
processes and note in general the presence of tigroid bodies in 
these. A single process, the axone or neurite does not possess 
these and may thus be distinguished from the remaining processes, 
the dendrites. Neuro-fib rillae extend throughout all the processes. 
Draw a good typical cell , showing the above named parts. 

2. Golgi preparations of nerve cells in sections of the cerebral 
and cerebellar cortex (Lab. SI. Coll.). These preparations, in 
which the neurones have been rendered black by the action of 
silver nitrate, are particularly for the purpose of showing the forms 
of the various cells and the course of their branches. They are 
thick preparations and do not as a rule permit the use of the high 
power objective. In some cases the axone may be distinguished 
from the dendrites by its smoother surface and its right-angled 
form of branching (cl. pictures of nerve cells in any good text-book 
of histology). Look particularly in the cerebral cortex for the 
characteristic pyramidal cells and in the cerebellar cortex for the 
Purkinje cells with their flask-shaped perikarya and enormous 
tree-like dendrites. Draw one or more good typical cells , and 
identify the types drawn by reference to some text-book of histology. 

3. Sections through the cerebral and cerebellar cortex stained 
to show the details of the cells of the different layers in situ (Lab. 
SI. Coll.). Study as many such sections as the time and material 
permit, identifying the layers and their characteristic cells by use 
of any good reference or text-book of histology. Note particularly 
the characteristic pyramidal cells of the cerebral cortex, and the 
Purkinje cells of the cerebellar cortex. Draw as much detail as 
you are able to identify and understand. 

B. NERVE FIBERS, THE PROLONGED PROCESSES OF 
NERVE CELLS. 

From the study of the following preparations note that there 
are two kinds of fibers, in both of which the essential part is the 
conspicuous, slender, non-nucleated column of protoplasm, known 
as the axis cylinder, which lies on the middle of the fiber and is in 
reality the much elongated process of some nerve cell. The 


HISTOLOGY OF NERVE TISSUES 


6l 

conspicuous structures in the preparations are the sheaths of these 
libers, in accordance with which the fibers are classified. 

Medullated Nerve Fibers. —These are the most abundant, 
and possess a double sheath, the outer a thin one of connective 
tissue cells known as the sheath of Schwann or the neurilemma, 
the inner one a thicker fatty layer (blackened by osmic acid) 
known as the medullary or myelin sheath, or the white substance 
of Schwann. The medullary sheath is not continuous, but is 
interrupted at regular intervals, the places of interruption appear¬ 
ing as constricted regions or nodes, and the length of fiber 
between two nodes forming an internode. Note that the sheath 
of Schwann is continuous over the nodes, and that it has one 
nucleus (which often bulges out conspicuously) for each inter¬ 
node of length. Note the double contour of medullated fibers 
in cross section, also the very great range of variation in size 
shown by the cross sectional areas. 

Non-medullated Nerve Fibers. —These are fewer in number 
than the medullated type, and are very inconspicuous. Each 
has a single sheath, the neurilemma, or sheath of Schwann, with 
here and there elongated nuclei which, as they bulge out from the 
side of the fiber, give it a peculiar wavy contour. 

Draw a sufficient length of nerve fiber of each kind y to 
show the above structures. Draw cross sections of medullated 
nerve fibers , showing the two sheaths and a nucleus of the outer 
sheath. 

1. Fresh teased preparation of nerve fibers made by teasing 
upon a dry slide a short length of small nerve taken from a recently 
killed animal (Necturus, frog, or some small mammal). During 
the teasing process the preparation should be kept from too rapid 
drying by breathing gently upon it, and the process of teasing 
should be continued until the separated fibers have dried 
dowm sufficiently to stay in place on the slide. Add a drop of 
physiological salt solution and cover. 

2. Teased preparations of nerve fibers previously hardened, 
and stained in haematoxylin (which stains the axis cylinder, the 
nuclei of the sheath, and the supporting, non-cellular meshwork 
of the medullary sheath), and mounted in Canada balsam (Lab. 
SI. Coll.). 


62 


MAMMALIAN ANATOMY 


3. Teased preparations of nerve fibers which were stained, 
while fresh, with osmic acid (which blackens the medullary 
sheath), and subsequently mounted either in glycerine or 
in Canada balsam (Lab. SI. Coll.). Note in addition to the 
above described features, the numerous oblique incisions in the 
medullary sheath. 

4. Cross sections of nerve fibers, stained with haematoxylin 
(Lab. SI. Coll.). In case these sections include the whole nerve, 
note the connective tissue sheath of the nerve as a whole, the 
perineurium, and the more delicate sheaths of the component 
bundles, the endoneurium. 

5. Cross sections of nerve fibers which were previously treated, 
while fresh, with osmic acid (Lab. SI. Coll.). 

C. NERVE ENDINGS (Lab. SI. Coll.). 

1. Motor Nerve Endings. 

Motor End Plates in Muscle Fibers. —Note the deeply stained 
axis cylinders of the bundles of fibers which enter the muscle mass; 
follow single fibers to their terminations in flat discs (end plates) 
one of which is applied to each muscle fiber. Note whether a 
single nerve fiber ever divides and supplies more than one muscle 
fiber. Draw. 

Study a single disc with great care under the high power. 
Note that the axis cylinder of the nerve fiber breaks up into a 
network or reticulum to form the disc. Draw details to show 
these points. 

2. Sensory Nerve Endings. 

Muscle Spindles, in Muscle Fibers. — Note that each spin¬ 
dle is differentiated from portions of several muscle fibers. Work 
out with care under the high power, the relation of the nerve fibers 
to the muscle spindle. Draw a single spindle showing details. 

Pacinian Corpuscles, in the Areolar Tissue of Mesentery or of 
the Pancreas of the Cat. —Note that the end of the nerve fiber is 
covered by numerous concentric wrappings of connective tissue, 
which serve as a mechanical means for transmitting stimuli to 
the nerve ending. Select slides in which the Pacinian corpuscle 
may be seen cut transversely and study the arrangement of these 


HISTOLOGY OF NERVE TISSUES 63 

parts. Select also a good longitudinal section through the middle 
of a corpuscle. Draw each view. 

Taste Buds, in the Epithelium of the Tongue (sections through 
the foliate papillae of the rabbit are recommended).—Note that the 
surface of the tongue is covered by a thick epithelium consisting 
of many layers of cells closely packed together. Note the differ¬ 
ence in shape of the cells of the superficial and deeper layers. In 
the epithelium which covers certain conspicuous folded regions 
(foliate papillae) identify the taste buds, each of which is a cluster 
of much elongated cells with their long axes at right angles to the 
surface of the fold. These differentiated epithelial cells are of two 
sorts, gustatory or taste cells and supporting cells. The gustatory 
cells, within the taste bud, are surrounded by the end arborizations 
of nerve fibers, which are rendered visible only by special methods 
of staining. Other branches of nerve fibers end among the cells 
between the adjoining taste buds. At its outer end each gustatory 
cell possesses a cilium which projects slightly from the surface 
through the opening of the organ, known as a taste pore. Draw 
a single good section through a taste bud , showing the relation of the 
cells to this pore. 

Olfactory Epithelium (teased or dissociated preparations are 
recommended; also sections of olfactory epithelium of some 
amphibian, stained with iron haematoxylin or other stain espe¬ 
cially adapted to bring out nerve cells and fibers).—The olfactory 
organ is peculiar in that there are present among certain tall 
columnar epithelial cells, other tall cells which are nervous in 
nature. Each of these has a short process (dendrite) which extends 
to the free surface, and another much elongated process (neurite) 
which is an olfactory nerve fiber and extends to the olfactory lobe 
of the brain. In the preparations supplied distinguish the two 
sorts of cells and draw a few of each , either in place or dissociated. 

The Retina 1 (slides showing vertical sections through the 
retina, e.g., of the rabbit and the frog).—Under the low power note 
that the staining methods used have disclosed the fact that the 
retina consists of many layers of structures of different thickness in 
different regions. Examine a carefully selected region under high 

1 This study of the retina may conveniently be postponed until after the study of 
the eyeball (p. 88). 


64 


MAMMALIAN ANATOMY 


power. Beginning with the most external layer, the layers of the 
retina are named and constituted as follows: 

i. The pigment layer (outside of this, the chorioid coat, 

also pigmented, and the sclerotic, are present in some 
of the preparations). 

ii. The layer of rods and cones, their apices directed toward 

the pigment layer. 

iii. The external limiting membrane, a delicate line, scarcely 

visible, and consisting mainly of the branches of the 
neuroglia, i.e., supporting cells. 

iv. The outer nuclear layer, a conspicuous layer exhibiting 

many deeply stained nuclei which are, for the most 
part, those of the nerve cells of which the rods and 
cones are the highly specialized processes. Among 
these, and indistinguishable in these preparations 
from them, are nuclei of neuroglia cells. 

v. The outer molecular layer, finely granular in appearance, 

because it consists of the cut ends of the delicate 
branches of the cells of the nuclear layers between 
which it lies. 

vi. The inner nuclear layer, consisting of bipolar nerve cells, 

the deeply stained nuclei of which give the name to the 
layer. 

vii. The inner molecular layer, with a structure similar to 

that of the outer molecular layer. 

viii. The ganglion cell layer, consisting of ganglion cells the 

rather large nuclei of which indicate the extent of the 
layer. 

ix. The nerve fiber layer, consisting of the fibers of the 
optic nerve, which are for the most part neurites of 
the cells of the ganglion cell layer. These fibers con¬ 
verge from various parts of the retina toward the point 
of exit of the optic nerve on its way to the brain (i.e., 
the blind spot). 

Compare these slides with the pictures in the various text¬ 
books of histology, and with the laboratory charts. Draw a 


HISTOLOGY OF NERVE TISSUES 65 

diagram from the slide showing the location of the various layers and 
any details which you can see clearly. 

The Spiral Organ of Corti 1 (slides showing sections through the 
cochlea of the ear of the pig are recommended).—Locate in the 
section a transverse section through a turn of the cochlea. Study 
this under low power and note the rounded form of the bony tube; 
the triangular form of the section through the ductus cochlearis, 
in which the spiral organ of Corti lies supported on the lamina 
basilaris (basilar layer) which stretches between the bony shelf 
(the lamina spiralis ossea) and the opposite wall of the tube; the 
scala vestibuli, separated from the ductus cochlearis by a delicate 
membrane usually torn in the sections (the membrana vesti¬ 
bularis Reissneri); the scala tympani, separated from the ductus 
cochlearis by the lamina basilaris; the membrana tectoria, sup¬ 
ported from the lamina spiralis ossea and overhanging the spiral 
organ; the spiral ganglion of the cochlea, lying in the lamina 
spiralis and sending nerve bundles beneath the lamina spiralis to 
reach the spiral organ of Corti. 

Under the high power study the details of the spiral organ of 
Corti. Note within this, the rounded triangular section of a cavity 
which accompanies the spiral organ through the windings of the 
cochlea, and is known as the tunnel. The base of this rests 
on the lamina basilaris, and the two sides are formed by the rods of 
Corti. The larger portion of the spiral organ of Corti lies on the 
outer side of the tunnel and consists of numerous tall epithelial 
cells specialized from the general epithelial lining of the ductus 
cochlearis, and supporting other more highly specialized cells, 
known as the outer hair cells from the fact that they bear on their 
exposed surface a group of short hair-like processes. On the inner 
side of the tunnel is a single row of inner hair cells, similarly 
supported by adjoining epithelial cells. These hair cells are the 
structures which are stimulated by the sound vibrations and 
transmit the stimuli to the nerve endings (visible only with certain 
methods of staining) of the auditory nerve fibers. Show by 
diagram made from your study of the cross section the general features 
of the cochlea and of the spiral organ of Corti. 

1 This study of the Organ of Corti may conveniently be postponed until after the 
dissection of the ear (pp. 92-94). 


IX. STUDY OF THE SPINAL CORD AND PERIPHERAL 

NERVOUS SYSTEM 

# 

A. GROSS ANATOMY. 

Study demonstration dissections of cat or other small mammal 1 
showing the whole spinal cord and spinal nerve roots (i) in situ , 
and (2) removed from the neural canal. Examine, also, short 
lengths of the spinal cord of some larger mammal (calf, lamb, or 
pig), with the dura mater removed in order to show better the 
external surface of the cord and the relation of the nerve roots 
to it. From these various preparations note the relation of the 
dura mater, arachnoid, and pi a mater to the cord and to the 
nerve roots; the general form of the cord with its cervical and 
- lumbar enlargements and its gradually tapering posterior end 
forming the filum terminate which, together with the more 
posterior pairs of spinal nerves, forms the tail-like structure known 
as the cauda equina; the ventral median fissure, and the dorsal 
median sulcus; the less sharply marked dorsal and ventral lateral 
sulci, the lines along which the dorsal and ventral nerve roots, 
respectively, leave the cord; the segmental arrangement of nerve 
roots corresponding to the intervertebral spaces, the more anterior 
roots passing out almost at right angles, while the more posterior 
ones have a very oblique posterior course; the presence of a 
ganglion on the dorsal (sensory) root; the point of union of the 
two roots. Draw. 

From more detailed dissections of a limited region, study the 
dorsal and ventral rami of each nerve, the former distributed 
mainly to the skin and skeletal muscles, the latter to the deeper 

1 New born or very young kittens furnish excellent material for these prepara¬ 
tions. They should be skinned while fresh, and the roof of the cranial cavity 
removed. The abdomen also should be laid open by a longitudinal slit. They 
should then be hardened for several weeks in 5% formalin made up with 30% alcohol 
(see p. 75) instead of water. When thoroughly hardened they may be washed out 
for a day or two in water and then dissected. They may be kept from year to year 
in 70% alcohol, or in 5% formalin. 

66 


s 


STUDY OF THE SPINAL CORD 


67 


muscles and viscera; and the communicating ramus between each 
spinal nerve and the corresponding ganglion of the sympathetic 
trunk. Draw. 

Examine other demonstration preparations made by dissecting 
from the ventral side. In making these it is necessary to remove 
much of the ventral musculature, and to lay open the thoracic, 
abdominal and pelvic cavities and remove most of the contained 
viscera, as well as the dorsal portion of the parietal serous mem¬ 
branes. The following are the more important structures to be 
seen: 

The course of the vagus nerve (and its accompanying sympa¬ 
thetic trunk), from its ganglion, which is located immediately 
posterior to the jugular foramen, through the whole length of the 
neck and the thoracic cavity, where it gives off branches to heart 
and lungs, and then continues through the diaphragm to the 
surface of the stomach where it enters into the formation of a 
plexus. 

The phrenic nerve which arises from a plexus formed by the 
ventral rami of the cervical nerves, and proceeds through the 
thoracic cavity passing over the surface of the heart to innervate 
the diaphragm. 

The brachial plexus formed from the ventral rami of the last 
three cervical and the first thoracic nerves, and located in the 
region between the anterior portion of the thoracic wall and the 
axilla. Follow ulnar, median, and radial nerves into the forearm 
and hand, noting the presence of both cutaneous and muscular 
branches. 

The lumbosacral plexus formed from the ventral rami of the 
posterior lumbar and anterior sacral nerves, and located in the 
dorsal wall of the pelvic cavity. Among its many branches may 
be distinguished the femoral branch which passes under the ingui¬ 
nal ligament to the medial side of .the thigh, and the very large 
sciatic branch which bends about the greater sciatic notch and 
passes to the back of the leg dividing in the lower leg into medial 
and lateral popliteal branches. Note the presence of both 
muscular and cutaneous branches. 

The delicate sympathetic trunk located upon each side of the 
mid-line back of the serous membrane in the dorsal wall of the 


68 


MAMMALIAN ANATOMY 


whole coelomic cavity. Each trunk consists of segmentally 
arranged chain ganglia joined together serially by slender con¬ 
nectives. Note that the sympathetic trunks extend through the 
neck region accompanying the vagus nerves, but that there are 
only three pairs of cervical ganglia. The most anterior of these 
lies close beside the ganglion of the vagus, and the middle one is 
located in close proximity to the very large stellate ganglion, the 
most posterior of the series, immediately anterior to the first 
rib. Each stellate ganglion gives off a branch to the vagus of 
that side and another branch which joins one from the vagus to 
be distributed to the plexus of the heart. 

Note that the lower thoracic ganglia give off nerves, among 
them the greater and lesser splanchnic nerves which connect with 
the coeliac ganglion posterior to the stomach. 

Draw such details of the preparation as you are able to see clearly 
and to understand. 

B. STRUCTURE OF THE SPINAL CORD. 

i. Macroscopic Study. —With a wet section knife make a clean, 
thin transverse section of a piece of well hardened spinal cord 
(10% formalin followed by 70% alcohol has been found to give 
good results). Place one or more of these in water in a clear glass 
watch crystal and examine it over a black background with a 
dissecting microscope, for the general topography of the cord. 
For comparison examine macroscopically over a white back¬ 
ground, stained transverse sections (Lab. SI. Coll.) through 
various regions of the cord, some of which show sections also of 
the spinal ganglia. In each of these preparations note whether 
or not the dura mater is present and its relation to the nerve 
roots and ganglia, when these also are present in the section. 
Make out the following points in the general topography thus 
studied: 

The median ventral fissure and the less conspicuous median 
dorsal sulcus, both reaching nearly to the center of the section; 
the less sharply marked dorsal lateral and ventral lateral sulci, 
and the relation of these to the nerve roots. 

The section through the gray nerve substance which presents 
an H shaped area with the lumen of the canalis centralis lying 


STUDY OF THE SPINAL CORD 


69 


in the cross bar of the H. The dorsal column of gray substance 
forms the dorsal region of the upright stroke of the H, the region 
opposite the cross bar is the lateral column, and the rounded 
region ventral to the cross bar is the ventral column. The latter, 
unlike the more pointed dorsal column, fails to reach the surface 
of the cord. 

The three funiculi of white substance upon each side, the 

dorsal one located between the median dorsal sulcus and the dorsal 
column of gray substance, the lateral one located between the 
lateral surface of the cord and the lateral boundary of the gray 
area, and the ventral one located between the ventral column of 
gray substance and the median ventral fissure. 

Compare sections through as many levels of the cord as are 
afforded by the material, and note the varying shapes, and the 
different proportionate amounts of the gray and white substance 
at different levels. Draw a section through two or more of the levels 
thus studied and show the general topography in each , noting in 
all cases the indefiniteness of the line separating the gray from the 
white substance. 

2. Microscopic Study. —Examine, mainly under low power, 
several sections of the spinal cord (Lab. SI. Coll.), and having 
established in each case the direction of the section with relation 
to the long axis of the cord, identify the following structures: 

The Meninges (dura mater, arachnoid, and pia mater).— 
Determine how many of these are present in each section, and the 
relation of each to the surface of the cord, the small root bundles 
(fila radicularia), and the ganglia, if these are present. 

The Epithelial Layer (ependyma) lining the canalis 
centralis, and any structures such as Reissner’s fiber, lying in 
the lumen. 

The Perikarya of Neurons in the Gray Nerve Substance.— 

In which column are these especially large and conspicuous? 
Where are they small and few? Are they at all grouped and where 
are such groups found? Look for sections which show the nucleus 
dorsalis (Clark’s column) in the dorso-medial region adjacent to 
the cross bar of the H. 

Fibers Extending from the Gray to the White Substance or 

vice versa .—Look especially for those which go to make up the 


7o 


MAMMALIAN ANATOMY 


fila radicularia of the nerves, and determine their relation to 
the gray nerve substance. 

Commissural Fibers. —Note that these lie either within the 
gray substance of the cross bar of the H (gray commissure), or 
ventral to the gray substance (white commissure). Determine 
so far as possible the connections which these make. 

The Longitudinal Bundles of Fibers (Fasciculi). —Note that 
these make up the bulk of the white funiculi, and are here cut 
transversely. Note, under high power, that these fibers are 

medullated. while the neurilemma is absent and a sheath of areolar 

* 

tissue takes its place. Compare with fibers seen in sections of 
nerve roots outside of the cord. 

Nerve Roots and Ganglion. —The general course of the dorsal 
root bundles of medullated fibers into and through the ganglion, 
between the groups of perikarya of sensory neurons. Why do the 
sections of the latter have rounded outlines? Are any of these cut 
through a process? Note the sheath of supporting cells around 
each perikaryon. Note the relation of the ventral root bundles to 
the ganglion. 

Select one good characteristic section , passing through a ganglion 
if possible , make of it as large an outline drawing as your page allows , 
to show the general topography as seen under the low power , and dll 
in in their proper regions the details of perikarya and fibers as studied 
under the high power . 


X. THE PRIMITIVE VERTEBRATE BRAIN 


The dogfish, a small species of shark, represents one of the 
most primitive groups of fishes, and its brain shows the simple 
form and arrangement of parts found in early embryos of higher 
vertebrates. It thus furnishes the key to the interpretation of 
brain structure in higher forms such as the mammals. 

A. DORSAL ASPECT OF THE DOGFISH BRAIN IN SITU. 

First, remove the skin, then carefully slice away the cartilage 
which forms the brain case (the animal has no bones) until the 
entire brain is exposed. The cartilage is translucent, and, if the 
dissection is done with care, before the nerves are reached they 
may be seen passing through the foramina and they may thus be 
preserved in connection with the brain. 

Study and draw the brain from the dorsal side , in situ, identifying 
the following brain vesicles and their parts: 

1. Telencephalon. —Olfactory lobes, cerebral “hemispheres.” 

2. Diencephalon. —Optic thalami, epiphysis (pineal body). 

3. Mesencephalon. —Optic lobes. 

# 

4. Metencephalon. —Cerebellum, with a median and two 
lateral lobes (flocculi). 

5. Myelencephalon. —Medulla oblongata. 

B. MEDIAN SAGITTAL SECTION OF THE DOGFISH 

BRAIN IN SITU. 

This section may be made by a single stroke by means of the 
w T et blade of a sharp thin knife or a section cutter through the 
median plane of the entire head. Study the brain as it appears 
in median sagittal section, identifying the following features, 
and recording the facts learned by means of a suitable drawing. 

1. Telencephalon. —Note the thickening, the corpus striatum, 
in the floor on each side, and the thinness of cerebral roof, or 
pallium, which forms the cerebral hemispheres. Each cerebral 
hemisphere contains a ventricle, the first and second, and these 

71 


72 


MAMMALIAN ANATOMY 


communicate in the midline through the foramen interventricu- 
lare with the third ventricle. 

2. Diencephalon. —Note the epiphysis (or pineal body) above, 
the hypophysis (or infundibulum) below, and the lateral thicken¬ 
ings, the optic thalami. The cavity is the third ventricle. 

3. Mesencephalon. —Trace the cavity, the aqueduct of the 
cerebrum, through this, and note that the optic lobes are dorso¬ 
lateral thickenings of the walls. 

4. Metencephalon. —Note its dorsal outpushing, the cere¬ 
bellum. 

5. Myelencephalon. —Note the wide fourth ventricle, and its 
thin roof. 

C. COMPARATIVE STUDY OF BRAINS OF OTHER 
VERTEBRATES. 

Examine other available demonstration dissections, such as 
the brain of some amphibian (Necturus or frog), and the brain of 
a reptile (turtle), a bird, and a primitive mammal (rodent), and 
identify the various brain vesicles and their more important 
features. 

Draw as many as time permits. 



1 


XI. THE MAMMALIAN BRAIN 


Material. —Each student should be provided with the head of 
a calf or sheep, obtained in as fresh a condition as possible from 
the abattoir. The head should be cut off well into the neck region, 
and the tongue left in place. The material is less expensive and 
more easily handled if the head is skinned, but at least one head 
should be sent with the skin on for the demonstration of external 
features and landmarks. The implements needed for the work 
are in addition to the usual dissecting instruments, a small saw, 
a % inch carpenter’s chisel, a wooden mallet, and bone forceps. 

Preparation of Material. —The specimen should be thoroughly 
washed under running cold water, and if it has been frozen it 
should be thawed before beginning the dissection. Make a rapid 
examination of the head externally, noting the relative position 
of various features, and identifying skeletal landmarks. Identify 
the structures shown in the cross section of the neck, and draw 
a diagram recording these. 

In case the specimen is not already skinned, remove the skin 
except around the mouth, the distal region of the nose, and the 
eyes, using for the purpose very sharp scalpels. The external 
ear may be removed with the skin. Note the adhesion of the 
skin to the frontal bone in the region medial to the superciliary 
arches where in the male the horns may be seen in various stages 
of growth. Remove the muscles from the lateral and posterior 
surfaces of the cranium, thereby exposing the temporal ridges and 
the occipital protuberance. Mark out with the scalpel lines 
along which to saw to remove the roof of the cranial cavity 
as follows: (i) an oblique line upon each side medial to and parallel 
with the superciliary arches, meeting each other in the midline 
anteriorly, and ending posteriorly just lateral to the temporal ridge; 
(2) an oblique line upon each side from the posterior end of the 
first line to the occipital foramen just medial to the occipital 
condyle. Use a small saw and take care to hold it at right angles 

73 


74 


MAMMALIAN ANATOMY 


to the surface of the bone. Take care not to saw too deeply and 
thus injure the surface of the brain which lies just beneath the 
bone. After sawing along the lines marked out, gently pry at 
various points with a chisel to determine if there are any regions 
which the saw has not completely separated, and, if such regions 
are found, cautiously chisel through them by light taps of the 
wooden mallet. Finally remove the bony roof by prying it up 
and detaching the adherent regions of the dura mater from its 
inner surface. This will expose the brain in situ covered by the 
dura mater. If there are portions of the roof which overhang 
the brain laterally, carefully chip these away with the bone 
forceps. 

From the exposed surface of the brain remove the dura mater 
including the falx cerebri, that thickening of the dura which dips 
into the longitudinal fissure between the two cerebral hemispheres, 
and the tentorium which lies in the transverse fissure between the 
cerebrum and the cerebellum. Beneath the dura mater may be 
seen the pia mater with its plexus of blood vessels. The arachnoid 
layer which lies between is too poorly defined to appear as a 
distinct membrane. 

To remove the brain from the cranial cavity, gently loosen it 
from the dura mater on all sides by means of the wet flat handle 
of a scalpel. Make sure that the tentorium is wholly removed. 
Lift the anterior end of the brain with care and, reaching in to the 
extreme anterior region of the floor of the cranial cavity with the 
wet scalpel handle, detach the olfactory lobes from the cribriform 
plate of the ethmoid upon each side. The anterior region of the 
brain may now be lifted up from the floor of the cavity. Then 
reach still farther back beneath the brain and, with a very sharp 
scalpel or with scissors, cut the optic nerves as far as possible from the 
ventral surface of the brain. If the head is now held in a vertical 
position with the nose pointed upward, gravitation will cause the 
brain to drop backward sufficiently to enable one to look in at the 
anterior end between the ventral surface of the brain and the floor 
of the cavity and see the stalk of the hypophysis, the carotid 
arteries, and the various pairs of cranial nerves which must be 
severed successively. As the process continues, the brain will 
fall farther and farther back and its weight should be supported 


THE MAMMALIAN BRAIN 


75 


by the hand. When it is finally free, place it in a deep dish of 
water, and examine it in its fresh condition. 

Finally harden it, for at least a week, in a mixture of alcohol 
and formalin (5% formalin in 30% alcohol), taking care to rest it 
upon cotton and not allow it to come in contact with the walls of 
the container. It is advisable that only one or two specimens 
should be hardened in a single container, and there should be at 
least a liter of the fluid for each specimen ( i.e ., 300 c.c. of 95% 
alcohol, 650 c.c. of water, and 50 c.c. of formaldehyde). Some of 
the hardening fluid should be gently forced by means of a syringe 
into the cavities of the brain through the opening in the stalk of 
the hypophysis upon the ventral surface. 

For the subsequent study of the brain it should be examined 
and dissected under water, and, after it is thoroughly hardened, it 
may be kept in water for several days without deleterious results. 

Preserve the head from which the brain was removed in 5% 
formalin. 

A. EXTERNAL FEATURES. 

Block out a general outline of the whole brain (xf) in very light 
lines from dorsal , lateral , and ventral aspects , and add to each 
drawing the various features as they are identified. 

1. Cerebrum (Telencephalon, Diencephalon, and Mesencephalon) 

Dorsal Aspect.- —Note that the roof of the telencephalon has 
become greatly thickened to form the two largest and most con¬ 
spicuous portions of the brain, the cerebral hemispheres, while the 
real anterior ends of the telencephalon, the slender olfactory 
lobes, are practically concealed from view. Note the deep 
median longitudinal fissure, separating the two hemispheres from 
each other; the frontal and occipital poles of the cerebral hemi¬ 
spheres, and the general division of each hemisphere into regions 
corresponding to the bones which form the cranial walls, and 
hence known respectively as the frontal, parietal, occipital, and 
temporal lobes. Note further that the convoluted appearance of 
the surface of the cerebral hemispheres is due to depressions, 
sulci, of varying depth, bounded by elevations or gyri. Note to 
what extent these are bilaterally symmetrical in arrangement. 
The sulci, the deeper of which are called fissures, may be followed 


* 


/ 


76 


MAMMALIAN ANATOMY 


out by carefully removing the arachnoid, pia mater, and blood 
vessels which fill them. The most conspicuous of these upon the 
dorsal surface is the central sulcus of Rolando, which is at right 
angles to the longitudinal fissure and partly separates frontal from 
parietal lobes; the upper end of the lateral cerebral fissure (fissure 
of Sylvius), mainly latero-ventral in location, which partly 
separates frontal from temporal lobes may also be seen. Note 
the general direction and arrangement of gyri and sulci in each 
area thus mapped out, and determine to what extent this 
corresponds to the arrangement in the human brain (cf. 
reference books). 

By gently removing the arachnoid from the longitudinal 
fissure, and pressing the cerebral hemispheres apart, the white 
surface of the corpus callosum may be seen extending across the 
midline between the two hemispheres. Posterior to this is located 
the small median outpushing of the roof of the diencephalon, 
the pineal body (epiphysis), the disclosure of which is made 
possible by the removal of the arachnoid from the transverse 
fissure. This allows the cerebellum to be bent gently backward 
thus making it possible to see also the four rounded eminences, or 
corpora quadrigemina, which form the dorsal portion of the 
mesencephalon. The pineal body lies in the depression between 
these and the cerebral hemispheres. 

Lateral Aspect. —Note the deep lateral cerebral fissure which 
crosses the lateral surface of the hemisphere vertically, thus form¬ 
ing the boundary between the frontal and the temporal lobes, while 
the supramarginal and angular gyri of the inferior parietal lobe 
arch about its upper end. By gently pressing forward the 
anterior wall of the lateral fissure, which is known as the oper¬ 
culum, it is possible to disclose at the bottom of the fissure a deep 
region of the convoluted surface of the cerebrum known as the 
insula, which will, however, be more plainly seen in the subsequent 
dissection. At its lower end the lateral fissure meets at right 
angles the rhinal fissure, which extends longitudinally the whole 
length of the cerebral hemisphere and may be better studied from 
the ventral aspect. 

Ventral Aspect. —Note the conspicuous rhinal fissure which 
crosses at right angles the ventral end of the lateral fissure, and 


THE MAMMALIAN BRAIN 


77 


continues posteriorly across the temporal lobe, forming the lateral 
boundary of the hippocampal gyrus; the olfactory lobes, and the 
olfactory tracts, which may be seen as whitish streaks diverging 
as they run posteriorly from the olfactory lobes. In the dien¬ 
cephalon note the optic chiasma in which the optic nerves come 
together and cross before continuing as the optic tracts which 
disappear from view laterally beneath the overhanging edges of 
the temporal lobes of the hemispheres; immediately posterior to 
the chiasma, the cut surface of the hollow stalk of the hypophysis; 
more posteriorly, a rounded elevation, the mammillary body. 

In the mesencephalon two large bundles of fibers, the peduncles 
of the cerebrum, may be seen to diverge from each other and 
disappear under the temporal lobes of the hemispheres. 

2. Rhombencephalon (metencephalon and myelencephalon). 

Dorsal Aspect. —Note the thickened roof of the metenceph¬ 
alon, the cerebellum, consisting of a median lobe, or vermis, and 
two lateral lobes, all with the surface much convoluted. Extend¬ 
ing posteriorly from beneath the cerebellum is the myelencepha¬ 
lon, or the medulla oblongata, the thin vascular roof of which 
(the tela chorioidea posterior) may be easily removed, exposing 
the interior of the fourth ventricle of the brain; note that the two 
narrow fiber tracts, the dorsal funiculi, which run longitudinally 
on each side of the dorsal median fissure of the posterior part of the 
medulla, and the two larger, laterally situated tracts, the lateral 
funiculi, are directly continuous posteriorly with the correspond¬ 
ing funiculi of the spinal cord. 

Ventral Aspect. —Note the floccular lobes of the cerebellum 
upon each side; the transverse band of fibers, the pons (Varolii), 
which connects the two sides of the cerebellum and thus forms the 
floor of the metencephalon; posterior to the pons, in the myelen¬ 
cephalon, a trapezoid body may be seen on each side; while on 
each side of the midline between the trapezoid bodies and 
extending posteriorly the whole length of the medulla are the two 
pyramids, continuations of the two ventral funiculi of the spinal 
cord and separated by the ventral longitudinal fissure; note that 
in the posterior region, bundles of fibers cross from each pyramid 
to the other (decussation of the pyramids); posterior to the 


78 


MAMMALIAN ANATOMY 


trapezoid bodies the pyramids are flanked laterally by the 
rounded elevations known as the olivary bodies. 

Nerve Roots. —(These are variously made up of sensory and 
motor components, indicated below respectively by the letters S 
and M. In certain cases, however, in which a nerve is designated 
as motor, small sensory components may also be present.) 

Olfactory (S) from 1 the olfactory lobes. These consist of 
many small bundles which are always torn from the olfactory 
lobes in removing the brain. 

Optic (S) from the optic chiasma. 

Oculomotor (M) appearing from the ventral surface of the 
cerebral peduncles. 

Trochlear (M) appearing laterally between the mesen¬ 
cephalon and the metencephalon, but arising from the dorsal 
surface at the posterior border of the mesencephalon. 

Trigeminal (M) appearing from the lateral border of the pons. 

Abducent (M) appearing from the lateral boundaries of the 
pyramids slightly posterior to the pons. 

Facial (S and M) from the latero-posterior borders of the 
trapezoid bodies. 

Acoustic (S) appearing laterally posterior to the pons. 

Glossopharyngeal (S and M) lateral to the olivary bodies. 

Vagus (S and M) from the lateral surface of the medulla 
posterior to the glossopharyngeal. 

Accessory (M) from many roots along the lateral surface of 
the spinal cord and medulla, these roots uniting and extending 
anteriorly as far as the root of the vagus, which they then accom¬ 
pany out of the cranial cavity. 

Hypoglossal (M) from the posterior region of the medulla 
along the lateral margins of the pyramids. 

B. INTERNAL STRUCTURE. 

i. Median Sagittal Section. 

Place the brain with the ventral surface up upon a layer of 
cotton on the table, and, using as a guide the midventral fissure, 

1 For convenience of description we may speak of both sorts of nerve roots as 
coming from the brain but in reality only the motor components actually originate 
from the brain, while the sensory ones grow into the brain from ganglia or from the 
sense organs themselves. 


THE MAMMALIAN BRAIN 


79 


make a median sagittal section through the entire brain by a 
single carefully directed stroke of the wet blade of a long 
thin sharp knife. Not more than half of the supply of 
specimens should be used for this purpose, and usually fewer 
will suffice since two students may conveniently study one good 
section. 

• 

The Cavities of the Brain. —The brain is a hollow organ, the 
walls of which have undergone repeated folding and thickening, 
and the cavity of which is continuous with that of the spinal cord, 
the canalis centralis. The inner surface of the cavity, covered by 
a smooth epithelium, the ependyma, should be carefully distin¬ 
guished from the cut surfaces of its walls. The cavities are known 
as ventricles, four in number and disposed as follows: The first 
and second (to be demonstrated by later dissection) in the two 
cerebral hemispheres, i.e., in the telencephalon, the third in the 
diencephalon, connected with the first and second by a channel 
known as the foramen interventriculare. The third ventricle 
is connected with the fourth ventricle, which is located in the 
rhombencephalon, by the aquasductus cerebri, which passes 
through the mesencephalon. The first and second ventricles are 
separated from each other by a thin median partition, the septum 
pellucidum, triangular in outline, and bounded above by the cor¬ 
pus callosum and below by a curved longitudinal bundle of fibers 
known as the body of the fornix. The anterior boundary of the 
third ventricle appears as a thin lamina, the lamina terminalis, 
extending ventrally from below the anterior end of the fornix to 
the optic chiasma. The roof of the anterior part of the third 
ventricle is very thin and is known as the epithelial chorioid 
lamina, through which the anterior chorioid plexus (blood vessels) 
pushes its way to reach the inner surface of the third ventricle. 
The extensive, thin roof to the fourth ventricle is revealed by 
carefully lifting up from contact with it, the overhanging thick¬ 
ened portion which forms the cerebellum. It consists of the 
anterior medullary velum, which lies anterior to the junction of 
the cerebellum with the medulla, and the posterior medullary 
velum, which lies posterior to the cerebellum. Through the 
latter velum the posterior chorioid plexus reaches the interior 
of the fourth ventricle. 


8 o 


MAMMALIAN ANATOMY 


Other Important Features Shown in the Sagittal Section.— 

The exposed wall of the longitudinal fissure formed by the medial 
surface of the cerebral hemisphere with its various gyri, the most 
definite and conspicuous of which is the gyrus cinguli which 
follows the dorsal curve of the corpus callosum; the dorsal and 
ventral outpushings of the third ventricle, which form the pineal 
body (epiphysis) and the hypophysis respectively (the latter, 
however, usually broken off in removing the brain from the cranial 
cavity); the massa intermedia, a soft mass lying in the middle of 
the third ventricle and appearing here as a cut area section, circular 
in outline; the cut surface of the cerebellum, with its tree-like 
arrangement (arbor vitae) of white nerve substance (bundles of 
nerve fibers) surrounded by the gray cortex; the commissures, i.e., 
bundles of fibers connecting the two halves and hence cut trans¬ 
versely here. These are ( a ) the corpus callosum, which connects 
the two cerebral hemispheres, ( b ) a portion of the fornix just 
ventral to the posterior end of the corpus callosum, (c) the optic 
chiasma, (d) the anterior commissure, very small, dorsal to the 
optic chiasma, and connected with it by the lamina terminalis, 
(e) the posterior commissure at the dorso-posterior limit of the 
third ventricle, (/) the pons. 

Draw the median sagittal section showing the cavities and other 
features , and making very clear the distinction between external 
surfaces, internal surfaces , and cut surfaces. 

2. Dissection of the Cerebral Hemispheres. 

Throughout this dissection draw details to show fact$ which you 
learn. 

For this, and the subsequent dissections, use preferably a 
w r hole brain, supplementing the material as needed by the half 
brains obtained by making the median section. Orient the dis¬ 
section by frequent reference to the external features of the brain 
and to the median sagittal section. Carefully cut away the 
dorsal surface of the cerebral hemispheres by making thin hori¬ 
zontal slices with a sharp wet razor or scalpel. While making this 
dissection note the distribution of white and gray matter, and 
latter forming a thick external layer, the cerebral cortex. Note 
that there are small bundles of fibers which extend beneath the 


THE MAMMALIAN BRAIN 


8 l 


cortex from one gyrus to another, while other bundles converge 
medially to enter into the formation of the corpus callosum, and 
still others take a more ventral course which will be further 
demonstrated later. With great care dissect down to the level 
of the surface of the corpus callosum, changing the direction of the 
sectioning as is needed to follow the curve of its upper surface 
and to trace it laterally into each cerebral hemisphere. If suffi¬ 
cient care is used it will be possible to disclose the delicate lateral 
and medial striae which extend in an antero-posterior direction 
along its free surface. By scraping or tearing lightly with the 
forceps, the transverse direction of the bundles of fibers of which 
the corpus callosum is composed may be demonstrated. 

With great caution continue the horizontal sectioning until by 
cutting through the lateral regions of the corpus callosum, in 
each hemisphere, the central part of each lateral ventricle is laid 
open. Finally cut through and remove the body of the corpus 
callosum leaving only the anterior bundles of transverse fibers 
which form its genu, and the posterior bundles which form the 
splenium, and exposing the cut upper edge of the septum pellu- 
cidum, the relation of which as a thin vertical partition between 
the two lateral ventricles will now be evident. Locate again the 
external surface of the insula and in the subsequent dissection do 
not slice away any of its cortex. 

Continue the dissection by cutting narrow wedge-shaped 
portions of the cerebral hemisphere away as need be to remove the 
roof of the anterior cornu, and of the extensive descending cornu, 
and thus lay bare the whole floor of the ventricle. Study the 
whole cavity and its relationships with great care. Note that 
the central part lies near the midline and was roofed over by the 
corpus callosum, while the septum pellucidum forms its medial 
wall, and a rounded eminence, the corpus striatum, lies in its floor 
and lateral wall. Note that the lateral wall is very thick and 
that the convoluted cortical surface of the insula forms the external 
boundary of this lateral wall. The anterior cornu of the cavity 
curves around the corpus striatum and extends into the frontal 
and olfactory lobes. The descending cornu curves ventrally into 
the temporal lobe, where it ends in that portion of the hippo¬ 
campal gyrus known as the uncus. The extensive rounded 


82 


MAMMALIAN ANATOMY 


elevation in the floor of the descending cornu is the hippo¬ 
campus. 

Forming a part of the medial wall of each ventricle is the body 
of the fornix, the two halves of which join in the midline (cf. 
median sagittal section) to form a triangular mass. Anteriorly 
the fornix takes the form of two columns of fibers which curve 
ventrally and disappear (since they pass into the thick mass 
which forms the floor of the cavity, and then curve posteriorly to 
reach the mammillary bodies, from which they pass dorsally to 

reach the optic thalami in the lateral walls of the diencephalon). 

✓ 

Posterior to the body of the fornix, its two crura diverge rapidly, 
and each forms the thin border, or fimbria, of the corresponding 
hippocampus. This may be disclosed upon one side by removal 
of the chorioid plexus which supplies the interior of the lateral 
ventricles, entering along the line between the corpus striatum 
and the fimbria where there is only a thin epithelial lamina. 
Draw the brain thus dissected to show the floor of the lateral ventricles , 
dorsal view. 

By gently detaching the ventral ends of the temporal lobes, 
the hippocampus and the adjacent remaining portions of the 
temporal and occipital lobes may be lifted in one piece and turned 
forward, displaying beneath them the dorsal surface of the dien¬ 
cephalon and the mesencephalon which this portion of the cerebral 
hemisphere overlaps. Note that in the middle of the diencephalon 
anterior to the pineal body there may be seen the chorioid plexus 
which forms the thin roof of the third ventricle. By removing 
this the narrow slit of the third ventricle is disclosed from above, 
between the thick walls formed by the optic thalami. If the 
reflected portion of the cerebral hemispheres be pulled well for¬ 
ward, the Y-shaped foramen interventriculare will now be seen 
beneath the body of the fornix connecting the lateral ventricles 
with the third ventricle. Cut through the body of the fornix and 
thus remove entirely the reflected portion of the cerebral 
hemispheres. 

3. Dissection of the Cerebellum. 

By a series of horizontal slices, remove the dorsal portion of 
the cerebellum until the level of the entrance, upon each side, of 


THE MAMMALIAN BRAIN 


83 


the various bundles of fibers from below into the cerebellum, is 
reached. Cut away the middle region or vermis of the cerebellum, 
which lies over the fourth ventricle, and carefully detach it, 
leaving in place as much as possible of the anterior and posterior 
medullary vela which form the actual roof of the cavity. Separate 
and identify the three bundles of fibers which enter the cerebellum 
upon each side as follows: (a) the brachium conjunctivum,which 
enters it from the dorsal portion of the peduncle of the cerebrum; 
(b) the brachium pontis which enters it from the pons; ( c ) the 
corpus restiforme which enters it from the lateral funiculus of the 
medulla. 

4. The Brain Stem. 

The dissection of the cerebral hemispheres and the cerebellum, 
as above directed, leaves that portion of the brain which cor¬ 
responds to practically the whole of the primitive vertebrate 
brain and is known as the brain stem. In the study of this, 
distinguish with care between those portions which are external 
surfaces, those which are interior surfaces of cavities, and those 
which are cut surfaces. Draw a dorsal view showing the parts 
identified; also , if time permits , a lateral view. 

In the telencephalon note the corpora striata which lie in the 
floor of the lateral ventricles; the thickness of the lateral wall of 
the ventricle, the cut surface of which displays a gray cortical 
layer and a converging mass of white substance adjoining the 
corpus striatum. This white substance consists largely of the 
system of projection fibers known as the corona radiata, which 
extends from the cerebral cortex through the corpus striatum to 
enter the cerebral peduncles and thus reach the more posterior 
portions of the nervous system. By making an oblique longi¬ 
tudinal section through one of the corpora striata, the course of 
these fibers through it may be seen, forming the “inner capsule” 
of the organ, and giving it the peculiar appearance from which it 
has derived its name. 

In the diencephalon note that the external surface of the optic 
thalami, which form its thick lateral walls, is exposed to view, and 
that between these rounded eminences the removal of the anterior 
chorioid plexus has disclosed anterior to the pineal body the slit- 


8 4 


MAMMALIAN ANATOMY 


like cavity of the diencephalon, the third ventricle, from which the 
foramen interventriculare leads on each side laterally into the 
lateral ventricles. Note the line along the surface of each optic 
thalamus marking the attachment of the chorioid plexus (the 
taenia thalami). On the ventral and lateral surfaces of the thala¬ 
mus note that the optic tract spreads out over the surface, a part 
of its fibers passing on to reach the geniculate body, which appears 
as a slight elevation in the angle between the thalamus and the 
midbrain, while still others enter the superior colliculus of the 
corpora quadrigemina. 

In the mesencephalon note that the exposed surface is wholly 
external surface. The four eminences of the corpora quadrigemina 
are known as the colliculi, the two superior colliculi being larger 
and nearer the middorsal line, while the inferior colliculi are more 
laterally located. The trochlear nerves may now be plainly seen 
as they emerge from the dorsal surface of the brain posterior to the 
inferior colliculi. Note the large size of the cerebral peduncles 
which form the floor of the mesencephalon, and their connection 
anteriorly with the base of the cerebrum which they reach by 
passing medial to the optic thalami. Note their convergence 
posteriorly to disappear within the pons. 

In the rhombencephalon note the thin roof of the rhomboid 
fossa or fourth ventricle. If this thin roof has been removed, the 
whole floor of the rhomboid fossa is exposed to view, bordered 
laterally by the cut surfaces of the bundles of fibers which enter 
the cerebellum, and by the lateral funiculi of the medulla. 
Anteriorly the fossa closes in beneath the corpora quadrigemina to 
form the aquaeductus cerebri, and posteriorly it closes in similarly 
to form the canalis centralis of the spinal cord. In its floor may 
be seen bordering the longitudinal sulcus numerous paired eleva¬ 
tions which indicate the location of certain of the masses of gray 
substance or “nuclei'’ of the medulla. From one of these the 
bundles of fibers which make up the acoustic nerve may be seen to 
extend transversely beneath the epithelial lining of the fossa, to 
issue from the surface at the lateral margins. 


THE MAMMALIAN BRAIN 


85 


5. Demonstration of Horizontal and Transverse Sections through 
Mammalian Brains (Human if Available). 

Identify the structures which appear in the various sections, 
and endeavor especially to follow ( a ) the cavities through the 
various regions of the brain and ( b ) the main tracts or bundles of 
fibers, particularly those which make up the cerebral peduncles, 
and the various commissures. Draw and interpret as many as 
time permits. 


i 


t 


xn. THE CRANIAL NERVES AND SPECIAL SENSE ORGANS 


Material. —The head 1 of the calf or sheep from which the brain 
was removed; whole heads sawn sagittally for demonstration of 
general topography; one or two sheep (or calf) skulls sawn hori¬ 
zontally and sagittally, and disarticulated skulls. For comparison 
with human relationships, models and demonstration dissections 
may be used. 

A. THE GENERAL TOPOGRAPHY OF THE HEAD. 

One-half of the heads may now be sawn by a median sagittal 
section into halves. After thoroughly washing the sawn surfaces 
under running water study these sections for general topography, 
identifying the various bones, noting relation of nasal cavities, 
mouth, superior and inferior regions of the pharynx, oesophagus, 
larynx; nasal septum, hard and soft palates, tonsils between the 
pillars of the fauces, tongue, epiglottis, and glottis; openings of 
auditory (Eustachian) tubes; location and character of teeth. 
Cf. with similar sections of the entire head, in which the cranial 
cavity containing the brain is also included; also with models of 
the human head, median sagittal section. Draw, labeling the 
parts identified. 

B. THE FLOOR OF THE CRANIAL CAVITY. 

Study the floor of the cranial cavity, first fitting together the 
two halves if the head has been sawn. Use for comparison the 
previous study of the features of the bony floor of the human 
cranial cavity (p. 44). Note that here the floor is covered by the 
dura mater, which does not conform completely to the bony floor 
of the cavity. This is particularly true in the region of the sella 
turcica, where a fold of the dura forms a false floor, the diaphragma 
sellae, beneath which the hypophysis, is located. The hollow 
stalk of the hypophysis, severed in the removal of the brain, may 

1 This, after two or three weeks in formalin, should be washed for two or three 
days in running water to remove the formalin, and may be kept in water during 
the progress of the work in the intervals when it is not being used. 

86 


THE CRANIAL NERVES AND SPECIAL SENSE ORGANS 87 

be seen anterior to the edge of the diaphragma sellae, and upon 
either side of this stalk the cut ends of the carotid arteries appear. 
Note the relation of the folds of the tentorium to the lateral 
boundaries of the diaphragma sellae. 

By reference to the previous study of the ventral surface of the 
brain, identify the cut ends of the cranial nerves which pass 
through the dura mater to reach their respective foramina of exit 
from the cranial cavity. Draw this view of the floor of the cavity, 
showing these features. 

Make sure of the identification of the optic, oculomotor, troch¬ 
lear, abducent, and ophthalmic branches of the trigeminal nerve. 

With a very sharp scalpel or curved seeker carefully cut 
through the dura mater to trace each nerve forward to its place of 
exit from the cranial cavity into the orbital fossa. The optic 
nerve takes a very short course to reach the optic foramen. The 
trochlear nerve takes a very oblique course through the dura along 
the medial surface of the tentorial fold, which must therefore be 
dissected away from the nerve with great care not to cut or break 
the nerve itself. The abducent nerve passes through the exten¬ 
sive cavernous sinus which lies in the sella turcica lateral to the 
hypophysis, so that to follow the nerve through this sinus involves 
the removal of the spongy structure and clotted blood which fill it. 
The ganglion of the trigeminal nerve (the semi-lunar or Gasserian 
ganglion) lies beneath the fold of the tentorium lateral to the 
cavernous sinus. Follow the ophthalmic branches of this nerve 
forward to the place where, in company with the trochlear, 
oculomotor, and abducent, they pass through the superior orbital 
fissure into the orbital fossa. With these nerves traced, the 
removal of the remaining portion of the dura mater may be 
accomplished without injury to the various nerve roots all of 
which should be left intact. Draw the bony floor of the cavity 
with the dura removed, showing the relation of the various cranial 
nerves to their foramina of exit. 

C. THE EYE AND THE NERVE DISTRIBUTION TO IT. 

(Cf. model of human eye.) 

Taking care not to injure or lose the identity of the nerves 
which have been traced to their entrance into the orbital fossa, 


88 


MAMMALIAN ANATOMY 


chip away the roof of this fossa by means of bone forceps, and 
thus disclose the eyeball and its surroundings in situ. Keeping 
each nerve intact, remove bit by bit the packing of areolar tissue 
and fat until finally the various muscles and their innervation are 
correctly and conclusively demonstrated, and their identification 
made certain by reference to the accompanying tabulation. 

Record this dissection of the eyeball surroundings and innervation 
by a series of drawings. 

Early in this dissection, the large lacrimal (tear) gland will 
be noted between the eyeball and the outer dorsal region of the rim 
of the orbit. Incidentally, also, note the course of the superior 
and inferior ophthalmic branches of the trigeminal nerve, as they 
cross the medial and lateral regions of the orbit respectively, 
each giving off small branches to supply local regions. Skillful 
dissection will disclose, also, the ciliary ganglion (sympathetic) 
located lateral to the optic nerve. Note connections between 
this ganglion and the oculomotor nerve, and trace numerous small 
nerves from the ganglion to the eyeball. As the dissection 
continues, after the trochlear, abducent, and superior branch of 
the oculomotor nerve have been traced to the muscles which they 
innervate, and the relationships thus worked out have been 
recorded, these muscles, together with the optic nerve, may 
be severed a short distance from their insertion into the eyeball, 
and the eyeball thus in part set free may then be turned forward 
thus giving access to the muscles which are more deeply located 
and are innervated by the inferior branch of the oculomotor. 
Retain all of the nerve and muscle connections which are worked 
out so that after the dissection is completed, all of the relation¬ 
ships may be clearly demonstrated. 

The Eyeball (if possible fresh material should be used).—Note 
that in removing the eyeball the thin layer of skin, the 
conjunctiva, which covers the front, or exposed surface, of the eye¬ 
ball, has been cut leaving intact, probably, the thin, cartilage- 
supported, semilunar fold (third eyelid or nictitating membrane) 
which crosses obliquely the medial region of the eyeball and has 
connected with it a firm mass, the Harderian gland. These 
structures may be used, together with the lacrimal gland and the 
openings of its ductules under the lateral region of the upper 


Name of muscles in probable order of T „ . . T *.* t___ 

. Location Origin Insertion Innervation 

identification 


THE CRANIAL NERVES AND SPECIAL SENSE ORGANS 


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go 


MAMMALIAN ANATOMY 


eyelid, to determine whether the specimen is from the right or the 
left side. Note form and size of the eyeball, the point of attach¬ 
ment; of the optic nerve, and places of insertion of the various 
muscles. Remove these together with the associated fat and 
connective tissue. Note that the outer wall of the eye ball con¬ 
sists ;of a thick, tough, whitish, skeletal structure, the sclera, 
except in the region where the transparent cornea, resembling in 
life a watch crystal, takes its place on the exposed surface. 
Through the cornea the colored iris with a circular opening in the 
middle, the pupil, may be seen (cf. living eye), and through the 
pupil the crystalline lens, also perfectly transparent in life, but 
rendered opaque by preserving fluids. 

With the specimen under water carefully cut the wall of the 
eyeball along an equator which separates posterior from anterior 
halves, and thus open into the posterior chamber back of the lens. 
Note the §omewhat jelly-like vitreous humor filling this cavity, 
and the delicate retina lining it (frequently detached in the process 
of dissection); the latter, composed of nerve tissue, is the receptive 
organ for light stimuli (cf. microscopic study, pp. 63,64). Note the 
“blind spot” where the optic nerve enters. Outside of the retina, 
between it and the sclera, is the deeply pigmented chorioid layer. 

In the anterior half of the eyeball note the extent of the retina. 
The crystalline lens will be seen supported by a suspensory cap¬ 
sule from the circle of ciliary processes borne on the ciliary fold 
which lies between the chorioid and the outer circumference of the 
iris. Draw an internal view of ( 1) the posterior and (2) the anterior 
half. ; 

The small anterior chamber, filled with a watery fluid, the 
aqueous humor, lies in front of the lens and may be opened into 
from behind by carefully removing the lens and its capsule. This 
exposes the ciliary fold and the inner surface of the iris, in which 
there are both radiating and circular muscle fibers. Draw the 
interior of the anterior half with the lens removed. 

External Study of the Living Eye and Its Surroundings in 
the Human Subject. —Note eyebrows, eyelids supported by 
tarsal; cartilages and fringed with eyelashes; the thin skin (con¬ 
junctiva) which lines the eyelids and covers the front (exposed) 
surface of the eyeball; by turning back the eyelid, the outlines of 


I 


THE CRANIAL NERVES AND SPECIAL SENSE ORGANS QI 

the yellow tarsal glands, connected with the roots of the eyelashes, 
may be seen; the moist condition of the conjunctiva is due to the 
lacrimal secretion which reaches the surface of the conjunctiva 
through orifices of ductules above the lateral angle and is drained 
off through the orifices of the naso-lacrimal duct, which are located 
on the lacrimal papillae upon the eyelids above and below the 
medial angle. In this region also, look for the semilunar fold of 
conjunctiva (the nictitating membrane) and the lacrimal caruncle 
medial to it. Draw the eye with its surroundings as seen from the 
front. 

Examine the various optical models of the eye which demon¬ 
strate the method of formation of the Image of an object upon the 
retina, and the range of accommodation for vision of objects at 
varying distances. 

D. THE OLFACTORY ORGAN AND ITS ACCESSORIES. 

For this work students may group themselves in pairs, each 
pair being supplied with (i) a whole head from which the brain 
has been removed, and (2) a head which has been sawn as above 
directed in a median sagittal plane. The nasal region of the first 
should be sawn in a series of parallel transverse sections at right 
angles to the long axis of the nose and about 1}^ inches apart. 
In so doing be careful not to injure the tongue. Wash the sawn 
surfaces under running water to remove debris. In the case of 
the half heads, if the nasal septum is still in place, remove it, 
carefully noting what parts are of connective tissue, and of carti¬ 
lage, and identifying the bones which contribute to it. Make a 
careful study and comparison of these preparations, using each 
point of view as a means for identifying the structures which 
appear in the other one. Note the following points: extent and 
boundaries of the nasal cavities; nature of lining mucous mem¬ 
brane and devices for increasing its area; division of cavity into 
pars olfactoria, and pars respiratoria; the cribriform plate of the 
ethmoid, through the numerous fenestrae of which the fiber bun¬ 
dles of the olfactory nerves pass to reach the mucous membrane 
of the pars olfactoria of the nasal cavity; the conchae, with their 
supporting bony framework of the scroll-like maxillo-turbinal, 
maso-turbinal, and ethmo-turbinal bones. 


92 


MAMMALIAN ANATOMY 


Draw transverse sections at various levels, showing the structures 
and relationships which have been worked out, and a medial view of 
the interior of the nasal cavity. 

Dissect out the maxillary concha from the nasal cavity of the 
half head, leaving intact the surface of its anterior region upon 
which a small pore (the orifice of the naso-lacrimal duct) may be 
seen; cut away also the superficial layer of the nasal concha 
thereby laying open the sinus which it encloses; remove the freely 
projecting ends of the ethmoid conchse, and note the complicated 
character of the sinuses and scrolls thus displayed. In the walls 
of the nasal cavity as thus exposed, look for orifices leading into 
the frontal, nasal, and maxillary sinuses. Pass probes of fine 
wire, or other suitably flexible material, as far as possible into all 
probable orifices of this kind, including that of the naso-lacrimal 
duct, and after recording the location of each of these upon a drawing 
of the lateral wall of the cavity, complete the identification of 
these orifices by dissecting away the bony walls sufficiently to 
follow the probe .previously introduced until the relationships 
have been clearly determined. In the case of the naso-lacrimal 
duct note that the tube is one of considerable size which passes 
very obliquely through the outer plate of the maxillary bone and 
through the lacrimal foramen into the orbit of the eye. By means 
of dotted lines added to the drawing of the lateral wall of the cavity show 
the connections thus worked out between the nasal cavity and the 
various sinuses, and the course of the naso-lacrimal duct. 

E. THE EAR. (Cf. model of the human ear.) 

The internal ear, the real auditory organ, lies within the 
thickened or petrous portion of the temporal bone and consists 
of a thin-walled, complicated structure known as the membran¬ 
ous labyrinth, enclosed within a thin layer of bone known as the 
bony labyrinth. The membranous labyrinth is filled with a 
fluid known as the endolymph, and the space between the mem¬ 
branous and the bony labyrinth is filled with perilymph. Acces¬ 
sory to the internal ear, are the cavum tympani (middle ear) arid 
the external ear, which afford a continuous channel through which 
the sound waves reach the internal ear. 


THE CRANIAL NERVES AND SPECIAL SENSE ORGANS 


93 


The ear region may be reached by sawing horizontally through 
the head (or more conveniently the half head) just above the level 
of the internal acoustic meatus, the external acoustic meatus, 
and the pharyngeal orifice of the auditory (Eustachian) tube. 

The external ear consists of the auricle (usually removed in 
skinning the specimens) and the acoustic canal, which leads 
through the external acoustic meatus to the cavity of the middle 
ear, the cavum tympani, from which it is separated by the delicate 
membrane of the tympanum stretched across its inner end. By 
dissecting away the soft parts and carefully chipping off the bony 
roof of the acoustic canal and the cavum tympani, these cavities 
may be opened from above with the membrane of the tympanum 
in place between them. 

The cavum tympani communicates with the pharynx through 
the auditory or Eustachian tube \vhich may also be laid open from 
above. (There also open into the cavum tympani from below, the 
large cavities or “cells” of the mastoid bone, as may be demon¬ 
strated from a preparation of the human temporal bone sawn 
through the cavum tympani and the mastoid process.) 

The membrane of the tympanum bears attached to its inner 
surface, the first of a chain of three tiny bones, the auditory 
ossicles; this first ossicle is the malleus, and is in turn articulated 
with the incus, while the latter bears the stapes; the stapes has a 
ring-shaped portion which fits into the fenestra vestibuli, an open¬ 
ing in the bony wall of the vestibule of the internal ear. Thus 
sound vibrations which move the tympanic membrane are com¬ 
municated through this chain of bones to the perilymph and 
through this to the endolymph, and so stimulate the receptive 
organs which are in the lining of the membranous labyrinth. A 
second fenestra in the bony wall of the labyrinth, the fenestra 
of the cochlea, also opens into the cavum tympani beneath the 
fenestra vestibuli, and the membrane which covers it furnishes 
the amount of movability in the wall of the perilymph cavity 
necessary to permit the vibrations of the fluids. 

Two muscles may be seen in the cavum tympani, (i) the tensor 
tympani, which arises from the medial surface of the wall of the 
auditory tube and is inserted, by means of a tendon which is bent 
nearly at right angles, into the malleus, and (2) the stapedius 


1 


94 


MAMMALIAN ANATOMY 


muscle, which arises from the posterior wall of the tympanum and 
is inserted into the stapes. 

The finer details of the internal ear cannot be made out from 
such material as this, but much of the general topography can be 
determined. Starting with the internal acoustic meatus, note that 
both the acoustic and facial nerve enter the petrous portion of the 
bone. By chipping away the surface of the bone with the bone 
forceps follow the course of the facial nerve along the line bounding 
middle and internal ear, and note that the acoustic nerve, which 
is more deeply located, has a ganglion within the acoustic meatus, 
beyond which point its two divisions diverge, the cochlearis 
passing forward and the vestibularis downward and backward. 
By further chipping away the bone certain portions of the laby¬ 
rinth itself may be located. 

The labyrinth consists of a vestibule, which contains two 
distended portions of the membranous labyrinth known as the 
saccule and the utricle, connected with each other through the 
endolymphatic duct. From the vestibule leads (i) the very 
elaborate coiled structure, known as the cochlea, located ventral 
and anterior to it, and (2) the three delicate semicircular ducts-, 
located dorsal and posterior to it (cf. dissection of the dogfish 
showing these canals). The membranous portion of the cochlea 
connects with the cavity of the saccule through a slender duct 
known as the ductus reuniens. Within the lining of the vestibule 
and the cochlea are the receptive organs of the sense of hearing, the 
spiral organ of Corti (cf. p. 65), while the semicircular canals are 
the organs of equilibration. 

Show by diagram the relation of the parts of the ear. 

F. THE FLOOR OF THE MOUTH, AND THE TONGUE. 

With the aid of a saw remove from those specimens of sheep’s 
heads which were not sawn sagittally, all the remaining portion 
dorsal to the surface of the tongue, and study the tongue and 
floor of the mouth. Use for comparison, the previous study of the 
median sagittal section of the head, also the interior of your 
own mouth, viewed with a mirror, or the interior of the mouth of a 
fellow-student. Compare, further, with demonstration dissections 
and models of the human tongue and larynx. 


THE CRANIAL NERVES AND SPECIAL SENSE ORGANS 95 

Floor of Mouth. —Note the kind and arrangement of teeth, 
the grinders (molars) in the posterior region and the cutters 
(incisors) in front, separated from the molars by a toothless 
interval. Note in connection with this, the complete absence of 
incisors in the upper jaw. 

Note the tall papillae, filiform in shape, of the tactile variety 
in the lining of the cheeks, and beneath the tongue. 

The Tongue .—Note its shape and extent. It is a muscular 
organ capable of taking a great variety of forms (cf. movements 
of your own tongue). The whole upper surface is thickly covered 
by papillae, the majority of which are minute and of the filiform 
variety, tactile in function. Among these are distributed the 
true taste papillae of the fungiform type, small in the distal region 
of the tongue but very large in the proximal. Along each side 
of the tongue in the proximal half, find a double row of large 
papillae of a third type, the circumvallate, consisting of an elevated 
circular center, with a furrow surrounding it and a circular ridge 
surrounding the whole. Connected with the posterior part of 
the tongue, note the presence and position of the epiglottis, which 
guards the glottis, the orifice of the larynx. Locate by palpation 
the hyoid bone which forms the skeletal support of the tongue; by 
dissection demonstrate the median part, or body, of the hyoid and 
two pair of cornua, and note that the lesser cornua are attached 
to the skull by a series of ligaments, and cartilages or bones (cf. 
the styloid processes of the human skull), while the greater are 
attached by ligaments to the thyreoid cartilage of the larynx (cf. 
dissection of the latter, pp. 98-100). 

Draw a view of the floor of the month and the tongue. 


I 




XIII. THE THORACIC VISCERA (PLUCKS) OF SOME 

LARGE MAMMAL 

Material. —Thoracic viscera (lamb or pig) obtained fresh from 
the abattoir, with as little mutilation as possible. The whole 
length of trachea, and the larynx and tongue should be included, 
also, at the posterior end, a portion of the diaphragm (and the 
liver in the case of one or two specimens). 

Orientation and Identification of the Structures Present.— 
Although the liver is an abdominal rather than a thoracic organ, 
its presence in at least a single specimen will help in orienting the 
other organs, and incidentally the general form and appearance 
of the liver itself should be noted. Identify its various lobes, the 
gall bladder, and the cystic duct leading from it to the du6denum 
(the latter not present here). Cut off and preserve small portions 
(an inch or less in each dimension) of the liver in 70% alcohol or 
5% formalin for later study. In case the material is absolutely 
fresh, smaller portions may be preserved for imbedding and 
sectioning (see p. 22). 

Note that the outer surface of the lung is covered by the thin 
smooth visceral pleura, which is continuous with both the dorsal 
and the ventral mediastinal pleurae. Note that the heart, 
enclosed within the pericardium, lies (together with the large 
blood vessels which are connected with it) in the ventral medi¬ 
astinal space, and that the oesophagus and the dorsal aorta are in 
the dorsal mediastinal space. If the material is sufficiently 
complete, trace these, and also the posterior vena cava, through 
the diaphragm. Sever the trachea and the oesophagus an inch or 
two below the larynx. Dissect the oesophagus well away from the 
dorsal wall of the larynx, leaving it attached only at the anterior 
end where it joins the pharynx. Cut off and discard the distal 
half of the tongue, together with any hanging, ragged ends of 
muscles and fat, and preserve the larynx for later study in 5% 
formalin. 


96 


I 


THORACIC VISCERA OF SOME LARGE MAMMAL 97 

A. THE TRACHEA, BRONCHI, AND LUNGS. 1 

Inflate the lungs by means of a large blowpipe inserted through 
the trachea and guarded by a compressible rubber tube as a 
mouthpiece, which may be pinched together to prevent air 
returning from the lungs to your own respiratory passages. 

Note that each lung has a large posterior lobe and a smaller 
bilobed anterior one and that the right lung has an additional 
lobe which fits into the space posterior to the heart. 

With the dorsal surface of the material uppermost, expose the 
trachea by removing the oesophagus and turning the aorta forward, 
start at the anterior end and follow the trachea until it divides 
into the bronchi which enter the various lobes of the lung. By 
removing the lymph glands, fat, and areolar tissue from the 
surface of the bronchi and the pulmonary veins and arteries which 
accompany them into the various lobes of the lungs, the whole 
plan of the air and blood supply to the lungs may be worked out. 
The blood vessels should also be traced in the opposite direction 
to demonstrate their relation to the heart. Note that the pul¬ 
monary veins of the various lobes enter the left auricle of the 
heart, the thin dorsal wall of which is immediately ventral to the 
large bronchi. Show by diagram the whole plan of air and blood 
supply to the lungs. 

In a single posterior lobe trace out by teasing and tearing the 
soft tissues, the entire course of the bronchus and its branches, 
together with the course of the corresponding veins and arteries. 
Note that the arteries are anterior and lateral to the corresponding 
bronchial tubes, while the veins are medial and posterior to them. 
Draw this dissection. 

Note that the smaller bronchial tubes, as well as the bronchi 
and trachea, contain in their walls incomplete rings of cartilage, 
which, while insuring a constantly open condition of the lumen, 
allow at the same time a considerable range of variation in caliber, 
which complete rings would prevent. In the smaller tubes the 
rings become very irregular, and the ultimate branches, the bron¬ 
chioles, possess no cartilage. These, like the alveoli into which 
they lead, are too minute for demonstration by gross dissection. 

1 Keep the material in cold storage (or on ice) in wet wrappings at least until the 
study of the lungs is completed. 

7 


9 8 


MAMMALIAN ANATOMY 


Note that a fragment of lung tissue from which the air has been 
driven by pressure between the fingers, still contains so much air 
in its alveoli that it will float when placed in water. Finally 
detach the lungs and trachea from the heart and its large blood 
vessels by severing carefully, one by one, the pulmonary veins 
and arteries at a point as far distant from the heart as possible. 
Discard the lungs and preserve the heart for later study, either 
in cold storage or in 5% formalin. 

Examine with the microscope (Dem. SI. Coll.) cross sections 
of the trachea showing the cartilaginous rings of the walls and 
the ciliated epithelial lining; and sections through the lung 
showing the alveoli inflated, and their relation to the bronchioles 
which lead into them. Draw whatever you are able to identify in 
the way of details from these sections. 

B. THE LARYNX. (Cf. compare with dissections and models 
of the human larynx.) 

Note that the larynx is a differentiation of the anterior region 
of the trachea. In the walls of the larynx locate, by palpation, 
the broad thyreoid cartilage on the ventral and lateral sides, the 
signet-ring shaped cricoid cartilage with its narrow portion 
posterior to the thyreoid and its broad portion dorsal to it, and 
the pair of arytasnoids which project anteriorly, one upon each 
side, between the lateral borders of the thyreoid and the broad 
dorsal region of the cricoid. 

Note that the hyoid bone lies immediately anterior to the 
thyreoid cartilage, and serves as attachment for numerous muscles 
which are not associated with the larynx; the cut ends of these 
muscles are here seen, and should be carefully removed so as to 
expose the external surface of the hyoid bone, the relation of which 
to the thyreoid cartilage will then be made clear. In this dissec¬ 
tion preserve, if possible, the chain of ligaments and cartilages 
which serves to attach each of the lesser cornua of the hyoid to 
the skull, thus suspending the tongue and the larynx from the 
skull (see p. 95). 

By the usual method of dissection of muscles work out the 
musculature of the external (ventral and lateral) surface of the 
larynx, identifying (1) the pair of thyreohyoid muscles which lie 


THORACIC VISCERA OF SOME LARGE MAMMAL 


99 


one upon each side of the prominent median process (“ Adam’s 
apple”) of the thyreoid, with the origin and insertion which is 
indicated by their name; (2) the posterior end of each of the crico- 
thyreoid muscles extending from the posterior edge of the thyre¬ 
oid cartilage to the ventral region of the cricoid; (3) the insertions 
into the lateral surfaces of the thyreoid, of the inferior constrictor 
of the pharynx, which encircles the anterior end of the oesophagus 
and holds it firmly in place; (4) portions of the sternothyreoid 
muscles which have their insertion into the posterior border of 
the thyreoid cartilage. Draw either the ventral or lateral view of 
the larynx and hyoid bone showing this musculature. 

Remove the oesophagus from its attachment to the dorsal 
wall of the larynx by severing the constrictor of the pharynx upon 
each side. Cut transversely across the belly of the thyreohyoid 
muscle upon one side and reflect the two ends of the muscle. 
Make a clean longitudinal cut through the whole length of the 
thyreoid cartilage a little to one side of the midventral line, and 
carefully lift the anterior end of the piece thus separated and free 
it from its loose attachment to underlying parts taking care not 
to destroy the crico-thyreoid muscle, the extensive origin of which 
from the inner surface of the thyreoid will now be fully demon¬ 
strated. With this muscle intact, the detached portion of the 
thyreoid may now be completely reflected, thus making possible 
the dissection of the deeper muscles of the larynx, which should 
be identified from their location and attachment as follows: (1) 
the dorsal crico-arytaenoid or crico-arytaenoideus posterior, 
(2) the lateral crico-arytaenoid, (3) the thyreo-arytaenoid, and, 
(4) the arytaenoid muscles, transverse and oblique, vestiges of 
which may be seen stretching between the anterior ends of the 
arytenoid cartilages. Note, incidentally, that slender muscles 
pass forward from the laryngeal cartilages to the epiglottis. 
Draw a lateral view of this dissection. 

Lay open the larynx by a median incision through its whole 
length along the middorsal line. Note that the vocal folds of the 
mucous membrane, with their underlying elastic ligaments, 
stretch from their ventral attachment to the inner surface along 
the midline of the thyreoid, to the vocal processes of the aryten¬ 
oids, which lie beneath the mucous membrane on either side of 


) 

> 


> 


> » > 


IOO 


MAMMALIAN ANATOMY 


the dorsal midline. Above each fold is an elongated depression, 
the ventricle, which is bounded anteriorly by the ventricular 
fold. Note that while the vocal folds are approximated and 
stretched into the position for vocalization of the breath by the 
contraction of the cricothyreoid muscles which pull forward upon 
the thyreoid cartilage, the tension of the vocal folds is regulated 
by the various combinations of contractions of the other muscles 
of the larynx, which are inserted, as shown by the above dissec¬ 
tion, into the muscular processes of the arytamoids. Draw the 
interior view of the larynx. 

C. THE HEART AND LARGE BLOOD VESSELS. 

Remove the loose pericardial sac which surrounds the heart, 
noting that a reflected portion of the pericardium fits tightly to the 
heart and forms its outer layer. By palpation and by external 
examination locate the four chambers of the heart (i.e., right 
auricle and ventricle, and left auricle and ventricle), and identify 
the blood vessels connected with each. Draw dorsal and ventral 
views. 

Make a cross section near the apex of the heart to demonstrate 
the circular form of the cavity of the thick-walled left ventricle, 
and the crescentic form of the cavity of the thin-walled right 
ventricle. Note the tendinous attachments of the tricuspid and 
bicuspid (mitral) valves in the right and left ventricles, respec¬ 
tively. By probing, show that the pulmonary artery leads from . 
the right ventricle and the aorta from the left. 

Taking care to avoid the anterior and posterior venae cavae 
which open into the right auricle, make a longitudinal slit through 
the wall of both the right auricle and right ventricle, thus laying 
open the two cavities. Note the thin, distensible walls of the 
auricle, the place of entrance of the veins, the auriculo-ventricular 
orifice through which the blood leaves the auricle and enters the 
ventricle and the tricuspid valve which guards this orifice. Draw. 

Make a similar dissection of the left side of the heart, noting 
the entrance of the pulmonary veins into the auricle, and the 
bicuspid valve guarding the auriculo-ventricular orifice. 

Make an incision transversely through the pulmonary artery 
about an inch above the heart and look down toward the heart to 


THORACIC VISCERA OF SOME LARGE MAMMAL 


IOI 


see the three semilunar valves which guard the artery. Lay the 
artery open by a longitudinal slit passing into the ventricle and 
study the valves more carefully. Draw. 

Similarly dissect and study the semilunar valves of the aorta. 

Draw a diagram showing the physiological anatomy of the heart 
and large blood vessels , and indicate by arrows the course of the blood 
through them. 

D. PHYSIOLOGICAL DEMONSTRATIONS. 

1. The Contraction of the Heart in the Frog. 

The animal used for this purpose should be either pithed or 
etherized. Note that a complete cardiac cycle consists of (i) a 
wave of contraction (systole) which proceeds from auricle to 
ventricle and drives the blood on, emptying each part successively, 
and (2) a period of relaxation (diastole), during which the auricles 
refill from the veins, and the ventricle (the frog heart has only one) 
refills from the auricle. 

2. The Sounds of the Beating Heart in the Liviug Human Subject; 

By means of the phonendoscope (or some other form of 
stethoscope) or by placing the ear directly in contact with the 
chest over the region of the heart, listen carefully to the sounds 
and learn to distinguish them. The first sound is due to the 
ventricular systole and is attributable to a combination of causes 
among which the vibration of the contracting muscle is undoubt¬ 
edly the chief one. The second sound, which is the shorter 
and the sharper one, is caused by the sudden and simultaneous 
closure of the semilunar valves which guard the entrances to the 
pulmonary artery and the aorta, respectively. Determine the 
rate of heart beat when the subject is sitting, standing, and after 
vigorous exercise Record. 





XIV. THE BLOOD VESSELS 

■» i 

< 

A. GROSS ANATOMY OF THE ARTERIES AND VEINS. 

Preparation of Material (Cat, Rabbit, White Rat, or Guinea 
Pig) .—The study of the circulatory system of an animal is greatly 
facilitated by filling and slightly distending the blood vessels, 
previous to dissection, with some fluid which will solidify within 
the vessels and which, being brightly colored, will enable the 
student to follow the course of the various vessels with ease. 
Such a fluid injection mass may, moreover, be distinctively colored 
to differentiate the various parts of the circulatory system. 

There are many different injection masses used, the chief 
requisite in preparation for gross dissection being (i) that the 
liquid should flow freely through the small tubes or cannulas used 
to introduce it into the various vessels; (2) that the fluid should 
contain suspended particles too large to pass through the capillary 
vessels into the tissues; (3) that the coloring matter should not be 
soluble, as it would then not remain confined to the blood vessels, 
but would stain the surrounding tissues; (4) that the mass should 
solidify within the vessels, but not too rapidly. 

The following injection mass 1 fills the above requirements 
satisfactorily. Make a gelatine solution of one part gelatine to 
seven or eight parts (by weight) of water. Soak the sheets of 
gelatine in the cold water and gradually heat it until the gelatine is 
dissolved, taking care not to burn it. To one volume of dry corn 
starch (mixed with an amount of powdered dry pigment sufficient 
to give the requisite depth of color) add three or four volumes of 
the warm (but not boiling) gelatin solution. Mix thoroughly 
and strain, while the mixture is still warm, through a fine wire 
strainer into a small clean jar, which, to be used conveniently, 
should be wide mouthed and should not be filled more than half 
full. The mixture thus made may be kept for several days by the 

1 Cf. Rand, The Skate for Classes in Comparative Anatomy; injection methods. 
American Naturalist, Vol. XXXIX, p. 365, 1905. 


102 


THE BLOOD VESSELS 


IO 3 


addition as soon as it has solidified, of a sufficient quantity of some 
coal-tar disinfectant to cover the top with a thin layer. 

When the mass is to be used, first wash the disinfectant from 
the surface by means of cold water, then let the jar stand in a pan 
of hot water (but never boiling, since that would cook the starch) 
for a few minutes to melt the gelatine. Keep the water in the 
pan hot by changing it from time to time as the work proceeds. 
Lay in the same hot water the implements to be used, such as glass 
syringes, several glass cannulas made from glass tubing drawn out 
into a tapering nozzle for insertion into blood vessels, short 
lengths of rubber tubes for connecting cannulas with syringes, 
and a sponge, or mass of absorbent cotton. Artery clamps for 
the temporary closing of a cut vessel to prevent loss of the injec¬ 
tion mass when the syringe is withdrawn, are very convenient, 
though little plugs of cotton or the simple pressure of the finger 
may be used frequently for the same purpose. 

In injecting, fill the syringe with the thoroughly stirred injec¬ 
tion mass and then attach the rubber tube, into the end of which 
the glass cannula has been inserted. 

In case the injection is to be made through a small blood vessel 
it will be necessary to insert the cannula into a slit in the wall of 
the vessel before attaching it to the syringe, since, owing to 
the collapsible nature of small blood vessels, particularly veins, the 
most effective method of inserting the cannula is by blowing the 
edges of the slit open using the cannula itself with the rubber 
attached as a blowpipe, and thrusting the point of the cannula 
in as the slit opens up. 

In case the injection is made directly into the heart or some 
large vessel, the attachment to the syringe may be made, and the 
cannula itself filled with the injection mass, before it is inserted. 

In any case, after the insertion of the cannula is made and the 
syringe is attached, the injection mass should be driven in with a 
slow steady pressure of the piston, while the cannula is firmly held 
in place with the thumb and finger. Never force the injection 
against a decided resistance but if you have reason to believe 
that the injection is not complete, halt the process and seek for 
the source of the resistance. At times, the squeezing of hot water 
from a sponge over the region which is being injected, facilitates 


104 


MAMMALIAN ANATOMY 


the process, since if the process is unduly prolonged the injection 
mass will harden either in the cannula or the blood vessels. 
Moreover, a previous injection may at any time be supplemented 
by an application of warm water to melt it, and then injecting 
more of the mass at any desired point. When an injection is 
completed, the cannula is withdrawn, the escape of the mass 
prevented by a ligature around the vessel, or by an artery clamp, 
or simply by pressure from the fingers or a wad of wet cotton, 
while the specimen is held under a stream of cold water until the 
injection mass is hardened. 

To prepare the specimen for injection, lay back the skin from 
the ventral surface of the neck, trunk, and proximal region of the 
legs; open into the thoracic cavity by a longitudinal incision 
through the series of costal cartilages on each side of the sternum. 
Tie a ligature tightly around the sternum near its anterior end to 
prevent the escape of blood (and later of the injection mass) from 
the cut ends of the sternal veins and arteries. Sever the sternum 
transversely posterior to the ligature and, after freeing the pos¬ 
terior end from the diaphragm, remove it together with the stumps 
of the costal cartilages and thus expose the heart within the peri¬ 
cardium, in situ in the thoracic cavity. Carefully slit open the 
pericardium. From your previous study of the organ its parts 
may be readily identified. 

Open the abdominal cavity by a longitudinal incision a little 
to one side of the midline. Plug the rectum with cotton inserted 
through the anal opening, to prevent the escape of faecal matter 
(especially necessary in case the animal used is a cat). 

Identify by reference to the list given below, the various blood 
vessels through which the injections are to be made, and, where 
indicated, pass a ligature of coarse thread or fine cotton string 
about the vessel and tie the ends loosely in a single knot, laying 
them carefully out, one on each side so that they may be con¬ 
veniently drawn up tightly before the cannula is finally removed. 

i. Systemic Veins and Pulmonary Arteries with Blue. 

In case the animal is as large as an adult cat or rabbit, this 
injection may conveniently be made through the femoral vein 
which may be readily exposed upon either side in the angle between 


THE BLOOD VESSELS 


i°5 

the leg and the body, where it lies superficially beside the some¬ 
what smaller femoral artery. A ligature should be passed around 
the vein and its accompanying artery separately before the 
injection is begun. Insert the cannula by the method above 
described (p. 103) through an incision in the wall of the vein 
distal to the ligature, and inject toward the heart, i.e., in the 
direction of normal blood flow. The injection mass will thus fill 
the veins along the whole course from the point of injection to the 
heart and will, moreover, back into the other branches of the 
posterior vena cava and into the anterior vena cava until it meets 
the first valves guarding these. It will also go forward through 
the heart and fill the pulmonary artery and its branches. If the 
injection is not successful, the other femoral artery may be tried, 
or in the case of a small animal the injection may be made much 
more readily through one of the jugular veins in the neck region. 

2. Systemic Arteries and Pulmonary Veins with Red. 

Here again unless the animal is too small, the injection may be 
made from the femoral region through the femoral artery, and will, 
if successful, fill not only the whole arterial system (as will be seen 
by watching the progress of the injection mass in the numerous 
small arteries of the mesentery), but will force its way past the 
bicuspid valve of the heart and back into the pulmonary veins. 

In case the animal is too small for ready injection through the 
femoral artery, inject through the left ventricle directly through 
a puncture made through the thick ventricular wall by means of 
the cannula. If a plug of cotton is inserted as the cannula is 
withdrawn, the puncture may be successfully closed, though the 
elasticity of the thick muscular wall itself will usually accomplish 
this closure. 

3. Hepatic Portal System with Yellow. 

This injection may be made through any convenient mesenteric 
vein. If one place fails, clamp it and try another. Close by 
clamp or by temporary pressure of a wad of wet absorbent cotton, 
or by the finger. 

After injecting, cool the specimen under the cold water faucet, 
to harden the gelatine. Make a slit in the wall of the stomach and 


io6 


MAMMALIAN ANATOMY 


remove the contents under a stream of water. In case the animal 
is a rodent, e.g., rabbit, white rat, or guinea pig, ligate the large 
intestine near the entrance into it of the caecum, make an incision 
at each end of the caecum and, after introducing a tube from a 
cold-water faucet into one of the incisions, turn on the water 
gently to wash out the contents of the caecum. In case the animal 
used is a cat, the large intestine should be emptied by a similar 
method. This process, though somewhat unpleasant, obviates 
greater inconvenience later. The specimen may be kept on ice 
in moist wrappings, or in running cold water for two or three 
days, but if it is desired to work on it longer, it should be skinned 
and preserved in 5% formalin, followed as usual by thorough 
washing in water before using. 

Directions for Dissection. —In general, dissection consists in 
removing the connective tissue which surrounds the blood vessels 
and holds them to adjoining structures, and by this means follow¬ 
ing out the vessel and its branches to the organs or regions which 
they supply. As the main veins and arteries follow the same 
general course, it will often be necessary to follow them out in a 
given region simultaneously. In no case should a blood vessel 
be cut until its connections have been fully determined and 
recorded. 

The record of the dissection must be kept in the form of a diagram 
{or a series of diagrams) which may either combine both the venous 
and arterial systems, or, if showing the two systems separately, 
should indicate correctly their anatomical relationships. The 
direction of blood flow should be indicated by arrows , and colors 
{corresponding to those used in injecting ) may be used to distinguish 
the different systems. 

The most convenient order to take in dissecting is as follows: 

1. The anterior vena cava 1 and its branches, working anteriorly 
from the heart, first very carefully laying open the narrow anterior 
end of the thoracic cavity by cutting through the attachments of 
the first pair of ribs to the sternum. 

2. The anterior branches of the aorta which issue from the 
thoracic cavity just dorsal to the anterior vena cava. 

1 In certain primitive mammals, e.g., the rabbit, there are two anterior venae cavae, 
a right and a left. 


THE BLOOD VESSELS 


107 

3. The blood vessels of the thoracic cavity which comprise in , 
addition to branches of the anterior vena cava and the aorta, the 
entire pulmonary system of arteries (injected blue) and veins 
(injected red). 

4. The hepatic portal system and the mesenteric arteries. 

5. The branches of the posterior vena cava and the remaining 
branches of the aorta. 

List of the principal blood vessels to be identified: 

1. Systemic System. 

(a) Arteries (injected red). 

Aorta, leading from left ventricle and forming an arch from 
which the anterior branches are given off. 

i. Anterior branches: 

Brachiocephalic. 

Right subclavian. 

Right carotid. 

Left carotid. (This, in some species, e.g., cat, 
guinea pig, is a branch of the brachiocephalic.) 
Left subclavian. 

ii. Thoracic branches: 

Intercostals (several pairs). 

iii. Abdominal branches: 

Phrenic. 

Coeliac axis. 

Hepatic. 

Coronary ( i.e ., to the stomach). 

Splenic. 

Superior mesenteric (in some species, e.g., guinea 
pig, this is united with the coeliac axis). 

Suprarenals (paired). 

Renals (paired). 

Spermatic or ovarian (paired). 

Inferior mesenteric. 

Lumbar (in segmentally arranged pairs). 

Iliolumbars. 

Common iliacs (in some species, e.g., cat, there is no 
common iliac, the external and internal iliacs being 
given off from the aorta as separate branches). 


MAMMALIAN ANATOMY 


108 

External iliac, giving off branches to external pelvic 
region and continuing as the femoral artery into 
the leg. 

Internal iliacs, passing into the pelvic cavity where 
branches are given off to the bladder and other 
pelvic organs, and to the pelvic walls and the 
gluteal region (to trace these into the pelvic cavity 
the pubic bones must be separated by cutting 
through the symphysis). 

Caudal (median continuation of the aorta). 

( b ) Veins (injected blue). 

i. Anterior branches, entering anterior vena cava: 

Brachiocephalics, right and left (in case there are two 
anterior venae cavae, e.g ., rabbit, there are no 
brachiocephalics): 

Subclavian. 

External jugular. 

Internal jugular. 

ii. Thoracic branches: 

Right azygos, receiving intercostal branches, and 
entering the anterior vena cava. 

iii. Abdominal branches, entering posterior vena cava: 

Phrenics. 

Hepatics. 

Renals. 

Spermatics or ovarian (note lack of symmetry in 
right and left sides). 

Iliolumbars. 

Common iliacs, with divisions and branches corre¬ 
sponding to those of the iliac arteries. 

2. Portal System (injected yellow). 

This consists of branches from the digestive tract, pancreas, 
and spleen which unite to form the hepatic portal vein. 
This enters the liver and divides, distributing the blood to its 
capillaries. 


THE BLOOD VESSELS 


IO9 

3. Pulmonary System. 

(a) Arteries (injected blue). 

Pulmonary artery, leading from the right ventricle, its 
right and left branches distributed to the correspond¬ 
ing lungs. 

(b) Veins (injected red). 

Pulmonary veins from the various lobes of the lungs into 
the left auricle. 

B. THE CAPILLARIES. 

For the study of capillaries, it is necessary to use either thick 
microscopic sections or small fragments of tissues in which the 
capillaries have been injected. Study with care and draw the 
details of a small region of one or more preparations , noting in each 
case the adaptation of the form of capillary network to the structure of 
the tissue in which it is located. 

The following preparations are suggested: 

1. Transverse section of intestine: Note the capillaries of the 
villi and of the muscular coats. 

2. Section of tongue: Distinguish the capillary network of the 
various sets of muscles. 

3. Section of lung tissue: Note that the capillaries of the 
alveoli form an almost continuous layer in the alveolar wall. 

4. Surface mount of small pieces of injected mucous membrane 
of rodent colon, showing capillary network in relation to short 
tubular glands. 

C. STRUCTURE OF WALLS OF BLOOD VESSELS. 

Study cross sections of veins and arteries and compare as to 
thickness of the walls and form of lumen. Note that in both there 
are three doats, the tunica intima, comprising the endothelial 
lining (supported, in the case of the artery, upon an elastic mem¬ 
brane), the tunica media, consisting of layers of elastic connective 
tissue and plain muscle fibers (this layer in the veins possesses less 
of the elastic and muscle tissue and is mainly of fibrous connective 
tissue), and the tunica adventitia, consisting mainly of elastic 


IIO 


MAMMALIAN ANATOMY 


and fibrous connective tissue. Draw , showing characteristic 
differences. 

Examine sections through various organs for identification of 
veins and arteries which appear in such sections. 

D. LOCATION OF SUPERFICIAL BLOOD VESSELS IN THE 

LIVING HUMAN SUBJECT. (Cf. manikin and atlases or 

text-books for identification of vessels.) 

Arteries (distinguished from veins by the presence of a pulse). 
Carotid, facial, temporal, axillary, radial, femoral. 

Veins. —Jugular, axillary, femoral, popliteal, and in many 
regions of the body, particularly in the distal portions of the 
extremities, conspicuous meshworks of subcutaneous veins. 
Choose some region as, for example, the back of the hand or the 
flexor surface of the wrist, and carefully study this meshwork as 
to (i) symmetry of the two sides of the same individual, (2) 
amount of variation exhibited by different individuals, (3) the 
location of valves, readily demonstrated by exerting sufficient 
pressure between the region under observation and the heart to 
prevent the onward flow of blood, which thus distends the vein 
between the point where the pressure is exerted and the nearest 
valve, since the blood accumulates proximal to the latter and is 
prevented by it from flowing backward. Record by notes or by 
drawing. 

E. DEMONSTRATIONS OF THE MOVEMENT OF THE 

BLOOD. 

1. Demonstration of the circulation of blood in a three-day 
chick: Break the egg into a dish of warm physiological salt solu¬ 
tion, being careful not to rupture the yolk. With the naked eye 
and under the dissecting microscope note the general plan of 
circulation (cf. chart) and the pulsation of the heart. 

2. Demonstration of the movement of the blood 1 in the web 

1 In case a frog is used for this demonstration it should first be pithed and the 
part to be examined then pinned out, but not too tightly stretched, over an aperture 
in a sheet of cork and placed upon the microscope stage. Keep the parts moist with 
physiological salt. If a salamander be used, it may be anesthetized by placing it in 
a solution of chloretone and then examined under water in a watch glass or stentor 
dish under a binocular dissecting microscope or a low power of the compound 
microscope. 


THE BLOOD VESSELS 


III 


of the frog’s foot, in the tongue of the frog, in the external gills 
of a Salamander larva, or in the unpigmented region of the skin 
of an adult salamander: Under the compound microscope the 
movements of the individual corpuscles may be seen. Note the 
relative rate in the capillaries, in the artery which brings the blood 
to the capillaries, and in the vein which carries it away. 

3. Demonstration by means of the Circulation Scheme devised 
by Porter, 1 (or by some similar apparatus) of arterial and venous 
pressure and of the conditions affecting them. Record the facts 
learned from this demonstration. 

4. Demonstration of the pulse tracing. By means of some 
form of sphygmograph (e.g., Dudgeon, Marey, or Jacquet), 2 
make a pulse tracing from your own or another person’s radial 
artery, and, after suitably labeling it, spray it with a weak shellac, 
or dip it in a shellac bath, to prevent rubbing, and mount it in the 
laboratory book , accompanied by an explanation of your interpreta¬ 
tion. Note that the pulse tracing shows always a rapid ascent 
and partial descent, constituting the primary wave, followed by at 
least one smaller or secondary wave; the primary wave expresses 
the sudden expansion of the artery caused by the ventricular 
systole, and the secondary waves, the chief of which is 
known as the dicrotic wave, are due to the elastic vibration of 
the arterial walls. 

5. Demonstration of arterial pressure and the method of 
measuring it by means of some form of sphygmomanometer. 
This instrument is usually applied to the upper arm of the subject 
and consists of a device for exerting upon the arm pressure which 
is transmitted through the tissues to the brachial artery, thus 
tending to obliterate the radial pulse which the operator is simul¬ 
taneously keeping track of. The amount of pressure which is 
being applied is automatically registered and is cumulative, so 
that at the moment when the complete obliteration of the pulse 

1 Porter, Introduction to Physiology, pp. 511-519, also Science, 1905, XXI, 
pp. 752-754. The demonstration apparatus here referred to is obtainable from the 
Harvard Apparatus Company. Since this apparatus or any similar one which might 
be used, would be accompanied by a description of the method of using it, it has 
been deemed sufficient for the purposes of these outlines, to merely give references to 
the apparatus and to any special descriptions of its use. 

2 Beddard (and others), Practical Physiology, pp. 80-84. 


112 


MAMMALIAN ANATOMY 


occurs, the pressure which is registered equals the maximum or 
systolic arterial pressure. Make and record as many determina¬ 
tions of systolic arterial pressure as the time allows. To insure 
accuracy several determinations should be made upon the same 
subject by each student before any comparison can be made of 
the determination of arterial pressure of different individuals. 


XV. BLOOD 


A. HISTOLOGY OF BLOOD. 

i. Examination of Fresh Blood. 

Amphibian Blood. —This may be obtained from a freshly 
killed specimen of Necturus or from the cut surface left by snip¬ 
ping off the toe of a living frog. 

Add a little of the blood to a drop of physiological salt solution 
upon the middle of a clean slide, and cover at once with a clean 
cover-slip. Examine first under low power, then under high 
power, of the compound microscope. Note the erythrocytes, 
their color, shape as seen lying flat and also upon edge, shape and 
position of nucleus. Draw flat and edge views. Note the far less 
numerous leucocytes, with their varying sizes, granular cytoplasm, 
pseudopodia, and nuclei. Watch a single leucocyte for 5 minutes 
making sketches of it at half-minute intervals to detect amoeboid 
activity. 

Human Blood. —This may be conveniently obtained and 
mounted as follows: Prepare two clean cover-slips. Sterilize 
the surface from which blood is to be drawn (the skin of the finger 
at the base of the nail, the ball of the finger, or the lobe of the ear) 
by washing thoroughly with 70% alcohol applied by means of a 
little absorbent cotton. After the surface has dried do not allow 
anything to come in contact with it until the incision has been 
made. Sterilize a clean, sharp needle or lance by rubbing it 
thoroughly wdth a little cotton wet with 70% alcohol. Allow it 
to dry. Make a quick cut deep enough to allow the blood to flow 
out freely, press slightly to start the blood, but do not continue 
to use pressure. Place a drop of the blood thus obtained upon one 
of the cover-slips. Immediately apply the other cover-slip to 
this, thus spreading the blood in a thin film. Lay this double 
cover-slip wdth the film of blood between, upon a glass slide and 
examine it first under low, then under high power. Note the 
erythrocytes, rapidly losing their smooth outline which becomes 
indented at regular intervals (crenated). On this account fresh 

113 


8 


MAMMALIAN ANATOMY 


114 

preparations must be frequently made. Compare with the 
amphibian erythrocytes as to color, size, shape, and absence of 
nucleus. (This comparison may be made more conveniently and 
accurately if a mixed mount of human and amphibian blood in a 
drop of physiological salt solution be used.) By careful focusing, 
the thinner central region and thicker margin may be demon¬ 
strated. Note that the edge view exhibits a characteristic dumb¬ 
bell shape, although under perfectly normal conditions the 
erythrocytes have been found to be concavo-convex, resembling 
half of a hollow sphere. Note the collection of the erythrocytes 
into rouleaux. Draw a few erythrocytes from different aspects. 

Among the erythrocytes look for various kinds of leucocytes 
which, however, will be better distinguished from the stained 
preparations later. Note range of size, granules, nuclei. Draw 
a few leucocytes. 

2. Smear Preparations of Human Blood, for the Study of Leuco¬ 
cytes. 

Method of Preparation of Blood Smear. —The slide or cover- 
slip upon which the film of blood is to be spread should be abso¬ 
lutely clean and free from grease. “Bon Ami” is recommended 
as an effective cleaning agent. 

Take off directly upon the slide at about three quarters of an 
inch from one end, a drop of freshly drawn blood. Place the slide 
on the table and use a second clean slide as a spreader, by bringing 
one end of it in contact with the full width of the first slide on the 
side of the drop toward the middle of the slide and then slanting 
the spreader slide back toward the drop until, when it makes an 
angle of about 30° with the lower slide, it comes in contact with the 
drop which is thus made to flow across the slide in the angle 
between it and the spreader. The spreader, still held at an 
angle of 30° is then pushed steadily toward the opposite end of the 
slide, dragging the blood after it in the form of an evenly dis¬ 
tributed film upon the middle region of the slide. 

After spreading the film it should be carefully dried in air, 
care being taken not to allow anything to come in contact with 
it. Wright’s stain, which is a mixture of eosinate of methylene 
blue and eosinate of methylene azur in a nearly saturate solution 


BLOOD 


115 

in pure methyl alcohol, is now poured carefully upon the horizontal 
slide until the film is just covered by it. After standing thus for 
one minute the stain is diluted by adding drop by drop from a pip¬ 
ette enough distilled water to equal two or three times the volume 
of the stain. The diluted stain should then remain from five to 
ten minutes and should then be washed off gently with water. 

The slide should next be carried over in a horizontal position 
into a wide dish of distilled water for the purpose of differentiating 
the stain, and the washing continued until the more evenly spread 
portions of the film are yellowish or reddish in color. This should 
take from one to three minutes. The excess of water should then 
be drained off and absorbed by means of filter paper, and the 
preparation may then be put aside to dry. Since it is advisable 
to dry it as rapidly as posisble, the application of a very gentle 
warmth is recommended. When the drying is completed the slide 
is ready for examination. 

The differential staining makes it possible to distinguish 
between the varieties of leucocytes, which will be found scattered 
among the masses of pinkish orange erythrocytes. 

The following types should be identified (Cf. plates in refer¬ 
ence books showing the differences between the various types): 

a. Small mononuclear leucocyte (lymphocyte), with clearly 
defined, dark purplish-blue nucleus and a small amount of bluish- 
green cytoplasm in which a few reddish granules may be seen. 
These leucocytes vary in size from one to two times that of an 
erythrocyte, and constitute about 2o%-? > o% of all the leucocytes 
of normal blood. 

b. Large mononuclear leucocyte with the same general staining 
reaction as the small ones but less intensely so. The nuclei are 
proportionately smaller and are more variable in form from 
rounded to irregular. In size this type is from two to three times 
that of the erythrocytes. They constitute a very small percent¬ 
age, i%-8%, of the leucocytes of normal blood. 

c. Three varieties of polymorphonuclear leucocytes, all with 
very variable, irregularly lobed or subdivided nuclei, which may even 
appear to be fragmented into separate masses. These cells vary 
in size from two to three times that of an erythrocyte. The three 
varieties, distinguished from each other mainly by the differential 


MAMMALIAN ANATOMY 


116 

staining of granules in the cytoplasm which otherwise does not 
take up the stain, are as follows: 

Neutrophiles. —In these the nucleus takes a purple stain. 
The granules in the cytoplasm are so fine as to be hardly distin¬ 
guishable as separate granules, so that the reddish-purple stain 
which they take (showing them to be neutral rather than either 
acid or basic in their affinities) seems to impart its color to the 
whole cytoplasm. These are the most abundant of all the types of 
leucocytes, constituting normally 60% to 70% of all the leucocytes. 

Acidophiles or Eosinophiles. —These are characterized by the 
affinity for acids of the coarse granules in the cytoplasm. These 
granules in consequence take on a red color from the eosin and 
are thus conspicuous in an otherwise unstained cytoplasm which 
surrounds the purple nucleus. The acidophiles constitute only 
from 1% to 4% of the total number of leucocytes in normal blood, 
and are thus very difficult to find. 

Basophiles. —In these the nucleus stains only faintly and is 
thus inconspicuous. The coarse granules in the cytoplasm have a 
strong basic affinity and thus stain deeply with methylene blue 
while they may also take on a purplish tinge similar to that 
imparted to the fine granules in the cytoplasm. The blue-stained, 
coarse granules are, however, so conspicuous that they seem even 
to stand out from the surface of the cytoplasm. This is the least 
abundant variety of leucocytes, since they constitute less than 
1% of the whole number. They are therefore seldom seen in a 
single preparation. 

Identify as many varieties as you are able to find and draw 
each variety identified. 

3. The Blood Count by Means of the Haematocytometer.— 

Using the mount of human blood set up for this purpose, make 
the count of erythrocytes as directed by the method accompany¬ 
ing the apparatus, and compute from this the number of erythro¬ 
cytes in 1 cu. mm. of blood. Record the entire computation. 

B. GENERAL PROPERTIES OF BLOOD. 

1. Coagulation. 

Take a quantity (50 c.c. or more) of freshly drawn blood, 
which, if obtained from the abattoir, must be kept at a low tern- 


I 


BLOOD 


‘117 


perature during the transportation. Divide this into two parts. 
Set one portion aside, at ordinary room temperature, and, without 
disturbing it, observe from time to time during a period of half an 
hour or longer, the process of formation of the dark red clot, 
and its gradual shrinkage away from the sides of the container, 
leaving the yellowish serum as the liquid portion of the blood. 
Record your observations together with the exact time when each 
is made. Meanwhile, whip the second portion (25 c.c. or more) 
in a shallow evaporating dish, with a few twigs or broom corns, 
and note that as a result the formation of the threads of fibrin, 
which is an essential element in the process of clotting, is 
hastened, and that the agitation detaches the erythrocytes, which 
are normally held in the meshes of the fibrin, so that these remain 
in the serum when eventually the fibrin threads, clinging to the 
broom corns, are removed from the blood. Blood thus treated 
is known as defibrinated blood and remains indefinitely without 
clotting. 

2. Determination of the Proportions of Plasma and Cells in 

Freshly Drawn Blood. 

Use blood which has not begun to clot, or, if this is not avail¬ 
able, defibrinated blood (the latter will give the proportion of 
serum, rather than of plasma, to blood cells). Carefully measure 
a sample of the blood to be used, in the graduated tube of a 
centrifuge machine, and after subjecting it to the centrifuging 
process sufficiently to drive the blood cells, which are heavier 
than the plasma, to the bottom of the tube, determine the propor¬ 
tion of these by volume (approximately) by reading the gradua¬ 
tions corresponding to the various levels. Record. 

3. Specific Gravity of Blood. 

Determine the specific gravity of a drop of human blood by the 
following method: Place in a beaker a stock mixture of chloroform 
and benzol having a specific gravity of about 1055. Draw a drop 
of blood by the method already learned and shake it from the 
finger into the mixture. If it gradually sinks add chloroform 
drop by drop, stirring the mixture gently, until the drop of blood 
neither rises nor sinks but remains stationary at any level, thus 


n8 


MAMMALIAN ANATOMY 


showing that its specific gravity is equal to that of the mixture. 
If, on the other hand, the drop of blood floats add benzol gradually 
and stir the mixture in the same way until a mixture is obtained 
in which the blood will remain suspended at any level. Then 
pour the mixture into a tall cylinder and determine its specific 
gravity with the hydrometer. This will also be the specific 
gravity of the blood. In returning the mixture to the stock bottle, 
remove the blood by straining. Record your method of procedure 
and the result of the determination. 

4. Determination of the Percentage of Haemoglobin in a Sample 
of Blood by Means of Some Form of Haemoglobinometer. 1 

Follow carefully the directions for using this device. Record 
the percentage determined. 

1 The Tallquist hemoglobin scale is a convenient form for this work. 


1 


XVI. THE RESPIRATORY PROCESS 


A. LOCATION OF THE EXTENT OF THE LUNGS BY 

PERCUSSION. 

For this exercise the subject should be loosely and thinly 
dressed. Place the index finger of the left hand upon various 
regions of the thoracic and abdominal wall of the living human 
subject, and listen to the sounds produced when the finger is 
tapped with the middle and ring fingers of the right hand. Note 
that over the lungs there is a hollow reverberating sound which 
is absent from other regions. Record the extent of the lungs upon 
outline drawings of the body, or upon the Suzuki manikin. 

B. CHANGES IN THE DIMENSIONS OF THE THORAX 

AND ABDOMEN OF THE HUMAN SUBJECT DURING 

RESPIRATION. 

A group of students may conveniently work together in obtain¬ 
ing these statistics. The subject must be loosely and thinly 
dressed. The measurements of width (from side to side), and 
depth (from front to back), are taken with calipers (pelvimeter), 
the girth measurements with a tape measure, and the height 
above the floor with an anthropometer. The records should be 
made in millimeters, and should be based upon averages obtained 
from at least five independent measurements of the same subject. 

i. Horizontal Measurements. 


(a) At the Level of the Lower End of the Sternum. 



Girth 

Depth 

Width 

Index 

d/w 

At the end of a natural exDiration. 





At the end of a natural insDiration. 

At the end of a forced exDiration. 

At the end of a forced inspiration. 





















I 20 


MAMMALIAN ANATOMY 


( b ) At the Level of the Umbilicus (i.e., just above the crest of 
the os ilium). 



Girth 

Depth 

Width 

Index 

d/w 

At the end of a 
At the end of a 
At the end of a 
At the end of a 

natural expiration. 

natural inspiration. 

forced expiration. 

forced inspiration. 






2. Vertical Measurements. 

(a) Lower End of Sternum. 


Height above floor 


At the end of a natural expiration. 
At the end of a natural inspiration 
At the end of a forced expiration. . 
At the end of a forced inspiration. 


(b) Distal End of Clavicle. 




• 

Height above floor 

At the end of a natural expiration. 

At the end of a natural inspiration. 

At the end of a forced expiration. 

At the end of the forced inspiration. 




Make a summary of conclusions under four heads: 

1. The changes in the dimensions of the thorax during normal 
breathing. 

2. The changes in the dimensions of the abdomen during normal 
breathing. 

3. The changes in the dimensions of the thorax during forced 
breathing. 

4. The changes in the dimensions of the abdomen during forced 
breathing. 









































THE RESPIRATORY PROCESS 


I 2 I 


Compare results obtained from as large a number of subjects 
as possible to show different types of respiration. 

C. PNEUMOGRAPH RECORD OF RESPIRATORY MOVE¬ 

MENTS. 

A group of four students may conveniently work together in 
making these records. The subject should be dressed as for (A). 
Adjust the pneumograph to the chest at the level of the lower end 
of the sternum. Attach the tube to the tambour, the writing 
point of which rests very obliquely upon the smoked paper carried 
by a slowly revolving drum. When all is adjusted, one student 
may start the drum to revolve, and, with a stop watch, time the 
duration of the experiment to exactly one minute, at the end of 
which time the drum must be stopped. During this time the 
subject should face away from the apparatus, and should breathe 
normally, which may be best accomplished if he fixes his attention 
upon some subject foreign to the experiment. Separate records 
at different tercels on the drum may be made for each student of the 
group. The paper may then be removed, the record carefully labeled 
and passed through a shellac bath. Dry by laying it, smoked side 
up, upon a sheet of filter paper. The records may then be cut apart, 
mounted in the laboratory book, measured and interpreted as to the 
following particulars: 

1. Rate of respiration per minute. 

2. Comparison of duration of the act of inspiration, expiration, 
and the post-inspiratory and post-expiratory pauses. 

3. Comparison of steadiness oj movement of inspiration and 
expiration. 

D. THE MECHANICS OF RESPIRATION (THE “RESPIRA¬ 

TION SCHEME” OF PORTER). 1 

Not more than two students can work conveniently with this 
apparatus at one time. Make the experiments as directed 
(Porter, pp. 506-507). Record the experiments in the form of 
definite complete statements as to the conditions and results. 

1 This apparatus may be obtained from the Harvard Apparatus Company. See 
Porter’s Introduction to Physiology. 


122 


MAMMALIAN ANATOMY 


E. RESPIRATORY SOUNDS. 

By means of the phonendoscope adjusted with the end of the 
rod applied (i) to the region of the trachea, (2) over the apex of 
one of the lungs (beneath the clavicle), and (3) to the back at one 
side of the midline at about the level of the fourth intercostal 
space, listen to the sounds accompanying respiration. Try to 
distinguish (1) sounds of the air moving through larynx and 
trachea and (2) vesicular murmurs which are due to the opening 
up of the bronchioles and alveoli during inspiration, and which 
die away during the latter part of expiration. The subject should 
be loosely and thinly dressed. 

F. SPIROMETER MEASUREMENTS OF THE VOLUMES 

OF AIR CONCERNED IN RESPIRATION. 

At least five trials should be made for each measurement and 
the results recorded and averaged. Each student should make the 
records from his own respiration; two students may , however, con¬ 
veniently assist each other in obtaining the records. Record the 
measurements in cubic centimeters (1 liter = 1000 cu. cm.). 

1. The tidal volume, the amount breathed in and out in a 
normal respiratory act. Determine by measuring the amount of 
air breathed out in a normal expiration following a normal 
inspiration. 

2. The complemental volume, the amount which is taken in 
during a forced inspiration in excess of the tidal volume. Deter¬ 
mine by measuring the amount breathed out in a normal expiration 
after a forced inspiration and deducting the tidal volume already 
obtained. 

3. The supplemental volume, the amount which may be 
expelled by a forced expiration in excess of the tidal volume. 
Determine by measuring the amount of air breathed out in a forced 
expiration following a normal inspiration and deducting the tidal 
volume already obtained. 

4. The vital capacity (complemental plus tidal plus supple¬ 
mental volumes). Determine by measuring the amount of air 
breathed out by a forced expiration following a forced inspiration. 
Check by comparison with the sum of 1, 2, and 3. 


THE RESPIRATORY PROCESS 


123 


G. THE DEMONSTRATION OF THE NATURE OF EX¬ 
PIRED AIR. 

1. The Excess of Carbon Dioxide. —This may be demon¬ 
strated by two bottles connected with a mouthpiece which is so 
arranged that the inhaled air passes through lime water in one 
bottle and the exhaled air through lime water in the other. This 
arrangement is made by using as a mouthpiece a Y-tube, one 
arm of which is connected by means of rubber tubing with a glass 
tube which passes through the tightly fitting cork of one bottle, 
reaching nearly to the bottom of the bottle, while the other arm 
of the tube is connected with a glass tube which leads only a short 
distance below the cork fitted tightly into the other bottle. The 
first bottle has an open glass tube leading through its cork from 
the upper part of the bottle, while the second bottle has another 
glass tube leading from near the bottom of the bottle. Each 
bottle is filled half full with filtered lime water at the beginning 
of the experiment. A rubber tube attached to the stem of the Y- 
tube serves as a mouthpiece, and can be washed or renewed as 
needed. Breathe in and out through this apparatus for a short 
time and note the result. Milkin ;ss induced in lime water by a 
stream of gas passing through it is a test for carbon dioxide in the 
gas. Record the result , accompanying it by a diagram of the appara¬ 
tus. Finally empty the lime water out and thoroughly rinse each 
bottle, using a weak solution of hydrochloric acid if necessary. 

2. The Deficiency of Oxygen. —Invert over water, with its 
mouth submerged, a wide-mouthed bottle filled with air. By 
means of a bent tube passed under water and into the bottle 
breathe the contained air in and then out two or three times. Lift 
the bottle and, keeping its mouth down, quickly put a lighted taper 
into it. As a control burn a taper in a similar inverted bottle filled 
with air. A flame will not burn in an atmosphere of less than 17% 
of oxygen, i.e. } a tension equal to 129 mm. of mercury. Record 
your conclusions. 


XVII. THE DIGESTIVE SYSTEM 


A. GROSS ANATOMY. 

By means of dissected demonstration preparations 1 (cats, 
rabbits, or other mammals) supplied for this study, review the 
gross anatomy of the digestive system (cf. pp. 11-13) and record by 
drawing such details as have not been previously recorded in your 
work. 

Mouth. —Note its extent and boundaries; character of the 
cheeks, lips, teeth, roof of mouth, and tongue; the salivary glands 
(parotid, submaxillary, and sublingual) and the ducts leading from 
these to the mouth. 

% 

Pharynx. —Note extent; walls, especially the lateral walls in 
which the tonsils are located; various orifices opening into and 
from it as identified in previous study of the sheep or calf (cf. p. 86). 

(Esophagus. —Note relation to larynx and trachea; course 
through thorax and relation to other organs of the thorax; the 
muscular nature of its walls; its collapsed condition when empty; 
the character of its lining; the passage of its posterior end through 
the diaphragm to reach the stomach. 

Stomach. —Note its location with relation to the diaphragm 
and to the other abdominal organs; the extension of its mesentery 
to form the overhanging greater omentum and the relation of this 
to the spleen; the differentiation of the stomach into cardiac and 
pyloric regions; the pouch-like form of the cardiac region, with 
its fundus bounded by the greater and lesser curvatures; the 

1 These preparations may be made very conveniently by detaching from the 
coelomic wall the entire length of alimentary canal, together with its associated 
glands, the heart, the lungs, and as much as possible of the diaphragm, all held in 
their normal relationships by the serous membranes. In the neck region the oeso¬ 
phagus and trachea should be detached from the adjacent muscular and skeletal 
parts and the neck severed near the base of the skull. The head is thus kept in its 
relationship to the alimentary canal, while the rest of the body may be discarded. 
Further dissection may then be made to show salivary glands and ducts and the 
ducts of the liver and pancreas. In each region of the alimentary canal a sufficient 
length should be laid open to make possible the examination of the walls and lining. 

124 


THE DIGESTIVE SYSTEM 


125 


tubular form of the pyloric region; the pyloric sphincter muscle 
guarding the exit into the intestine; the muscular walls, and the 
deviation from the strict longitudinal and circular arrangement of 
muscle fibers thus giving rise to oblique layers; the character of its 
mucous lining with the numerous folds, an accommodation to the 
distensibility of the organ. 

Liver. —Note its location, voluminous size, and the form and 
arrangement of its lobes; the folds of the peritoneum supporting 
the liver and attaching it to the diaphragm (falciform ligament); 
the lesser omentum stretching between the liver, and the pyloric 
end of the stomach and anterior end of the intestine; the position 
of the gall bladder with ducts leading into it from the liver and the 
cystic duct leading from it into the anterior region of the intestine 
(duodenum). 

Pancreas. —Note its thin and irregular form due to its location 
within the mesentery between the stomach and duodenum, into 
which its duct leads. 

Small Intestine. —Note its length, involving convolutions and 
an enormous expansion of the ventral edge of the mesentery which 
supports it; the numerous blood vessels, lymph glands and vessels, 
fat deposits, and (especially conspicuous in the cat) small glisten¬ 
ing Pacinian corpuscles between the two layers of the mesentery; 
the muscular coats strongly differentiated into the longitudinal 
and circular layers; the velvety appearance of the mucous lining 
due to the villi which thickly stud its surface; the circular folds 
(valvulae conniventes) of the mucous lining; the differentiation 
of the first loop of the intestine as the duodenum, and the relation 
of this to the pancreas and its duct as well as to the cystic duct; 
the opening of the small intestine into the side of the large intestine 
(location of ileo-colic valve). 

Large Intestine. —Note its wider caliber; the blind end 
(caecum) extending beyond the opening of the small intestine 
into it (cf. the voluminous caecum of rodents, and the reduced 
caecum and the vermiform appendix of man); its differentiation, 
less clearly marked than in man, into ascending (right side), 
transverse, and descending colons, and rectum; thinner nature of 
the muscular walls, as compared with those of the small intestine, 
the absence of villi, and the smoother nature of the lining. 


MAMMALIAN ANATOMY 


126 

B. PHYSIOLOGICAL DEMONSTRATIONS. 

1. Peristalsis. —Use a recently chloroformed or etherized frog, 
Necturus, or mammal (preferably the latter) from a half hour to an 
hour after feeding. Expose the intestines by opening the abdom¬ 
inal cavity. Observe the waves of contraction which pass slowly 
along the intestine and note the changes of form which they 
involve, and their effect in producing an onward movement of the 
contents of the region which is under observation. Note that 
these movements may be induced by mechanical stimulation. 

2. Appearance of the Food in Different Regions of the Diges¬ 
tive Tract during the Process of Digestion. —The specimens 
(cats and rabbits) used for this demonstration should be killed 
about a half hour or an hour after feeding. Open various regions 
of the digestive tract and compare the condition of the food mate¬ 
rial found in different regions, also note the conspicuous differ¬ 
ences which result from the difference in normal diet in such 
animals as the cat (carnivorous) and the rabbit (herbivorous). 

Note particularly the slightly digested and thus still recog¬ 
nizable food substances in the stomach, the creamy chyle in the 
small intestine, and the gradual accumulation of faecal matter 
which is left after the absorption of the nutritive portions of the 
food and which becomes more abundant and offensive in odor as a 
result of bacterial decomposition as the posterior region of the 
intestine is reached. Note also the degree to which the faeces are 
moulded into characteristic shapes before expulsion. Note, 
incidentally, the distended lymphatic vessels (lacteals) of the 
mesentery and follow these to the receptaculum chyli and thoracic 
duct (especially well seen in a cat which has been fed with rich 
milk about half an hour previous to chloroforming). 

C. HISTOLOGY. 

♦ 

1. The Alimentary Canal. 

Macroscopic Study. —In preparation for the microscopic study 

► 

of the intestine, examine macroscopically a short length of intes¬ 
tine (cat) which has been thoroughly hardened in formalin or some 
other fixing agent. With a sharp-scalpel make a clean transverse 
section of this and examine the cut end. Tease or tear apart the 
various layers. Note (a) the visceral peritoneal layer which 


i 


THE DIGESTIVE SYSTEM 


127 


covers the whole outer surface forming the very thin serous coat 
(tunica serosa); within this, ( b ) the thick, firm muscular coat 
(tunica muscularis) consisting of a thin outer layer of longitudinal 
fibers which may be easily stripped off (together with the serosa), 
and a thicker inner layer of circular fibers; inside the muscularis 
(c) a layer of connective tissue (tela submucosa); and finally (d) 
the innermost layer (tunica mucosa) which is very conspicuous 
because of the innumerable absorbent organs (villi) which thickly 
cover its surface and project into the lumen. Note the velvety 
appearance which the inner surface presents when a short length 
of intestine is laid open and washed. 

Microscopic Study (Lab. SI. Coll.).—Examine cross sections 
of the intestine of an amphibian and identify the various coats 
above mentioned. Note that the serosa is continuous with the 
mesentery and consists of a single layer of flat cells showing in 
cross section as a thin line with occasional flattened nuclei; that 
the spindle shaped involuntary muscle fibers (each a single cell 
with a single nucleus) of the longitudinal layer are cut transversely 
and those of the circular layer are cut longitudinally; that there 
are numerous blood vessels in the various layers, particularly 
in the submucosa; that the mucosa has no villi as has the mam¬ 
malian intestine but is thrown into numerous longitudinal folds, 
here cut transversely, which would disappear if the intestine 
were distended with food; that these folds are covered by a simple 
layer of columnar epithelial cells among which are many cells 
of the goblet type, i.e., cells which pour out their mucous secre¬ 
tion from time to time into the intestine; that there are a few 
multicellular intestinal glands of the coiled tubular type, lined 
with simple epithelium and opening into the intestinal lumen 
between the folds. Draw the whole section on as large a scale as 
the size of the page will allow , and show the outlines of the various 
layers, filling in, in their proper places, representative details of 
cell structure. 

Examine cross sections of the small intestine of the rabbit, for 
general identification of layers. Note that here the muscular 
layers are very thin; that the mucosa possesses in addition to a few 
large folds, numerous villi, and a much larger number of intestinal 
glands, which are also larger and more complicated. 


128 


MAMMALIAN ANATOMY 


Examine longitudinal sections of the small intestine of the 
dog or cat. Note that the sections are so curved by the contrac¬ 
tion of the muscularis that the mucosa lies on the outer border of 
the section, the villi well separated. Under low power identify 
the layers, noting the occurrence of an additional thin muscle 
layer between the mucosa and the submucosa known as the 
muscularis mucosae; under high power study the details of villi and 
glands. Draw details showing (1) a longitudinal section through a 
villus , and (2) the form of a group of intestinal glands and their open¬ 
ings into the Imnen of the intestine. Occasionally compact masses of 
lymphoid tissue, known as solitary lymph nodules, will be seen in 
the submucosa. 

Study a preparation showing cross sections of individual 

villi. Draw one or two , as seen under high power. 

Study again cross sections of injected intestine to show the 
network of capillaries in the various layers, particularly in the 
villi. 

Study sections through various regions of the wall of the 
stomach. Note the same general arrangement of coats as in the 
intestine, with modifications in the form of oblique layers in the 
muscularis; the numerous deep folds of the mucosa, with tubular 
glands opening between them, peptic glands, of the simple or 
slightly branching tubular type in the region of the fundus, and 
pyloric glands, more branching and more convoluted, in form, in 
the pyloric region. Draw a view showing the general arrangement 
of layers as seen under low power; draw details of folds and glands 
of mucosa of the fundus and of the pyloric region under high power. 

Study sections of injected stomach to show capillary network, 
particularly of the mucosa. 

2. Special Digestive Glands. 

The primitive glandular structure, already studied in the case of 
the glands of the stomach and intestine, consists of an invagination 
of the epithelium, in the form either of a tube or of an alveolus, 
lined throughout with epithelial cells. When the invagination 
becomes so extensive and so complicated by branching that it 
forms a mass of tissue lying quite outside of the wall of the 
organ from which it arose, a distinct organ such as a salivary 


THE DIGESTIVE SYSTEM 


129 


gland, pancreas, or liver is formed. Such an organ may retain 
its connection with the epithelium from which it was derived, 
through a more or less elongated duct, the lumen of which on the 
one hand leads from the lumina of the various tubules or alveoli 
of the gland, and on the other hand opens into the lumen of the 
alimentary canal. The extensive and repeated branching of a 
gland gives rise to lobes which are thus composed either of masses 
of tubules convoluted for greater compactness, or of branched 
tubules ending in alveolar expansions (acini), or of clusters of 
alveoli, according to the nature of the gland. Each ultimate 
alveolus or tubule will thus communicate with the intralobular 
duct, and these in turn will lead into interlobular ducts which lead 
finally into the common duct of the gland. 

Salivary Gland (compound tubulo-alveolar). 1 —Review the 
general external form and appearance of a salivary gland with its 
many lobes and its discharging duct, noting its investment of 
connective tissue which holds the lobes together and conveys the 
blood vessels and nerves to the gland tissue. 

Study microscopically, sections of a salivary gland. Note 
the division into lobes, each exhibiting a compact mass of sections 
through the tubules and alveoli, among which may be seen 
occasional sections through the intra lobular ducts and their 
branches. Observe that the parts are held together by loose 
connective tissue, which is the interstitial tissue as distinguished 
from the parenchyma or true glandular tissue. Study under 
high power for details of structure as are peculiar to the gland in 
question, such as the form of lumen, the shape, size and arrange¬ 
ment of cells, nature of nucleus and cytoplasm, in the case both 
of the alveoli and of the ducts, and the distribution in the tubules 
and acini of serous and mucous cells. Note the presence of the 
zymogen granules in the serous cells, ready to be poured out as 
the liquid secretion of the gland. Draw such details as you see 
clearly and understand. 

Liver (modified type of tubular gland).—Examine macroscopi- 
cally pieces of pig liver hardened in alcohol or formalin, make fresh 
sections of it in various directions and note that it is a compact 

1 Sections of the pancreas may be substituted for this study, as a type of tubulo- 
alveolar gland. 

9 


130 


MAMMALIAN ANATOMY 


mass made up of numerous lobules, each having somewhat the 
form of two frusta of pyramids placed base to base and thus 
appearing in section in irregular polygonal form. Study micro¬ 
scopically, sections of the liver of various mammals (the pig par¬ 
ticularly), for the relation of the lobules to each other and the 
identification of blood vessels and bile ducts shown in a transverse 
section of a lobule as follows:. Running through the center of 
each lobule is a small vein (the intralobular vein) which collects 
the blood from the capillaries of the lobule, while in the connective 
tissue at the angles between lobules (interlobular) are the ultimate 
branches of the hepatic portal vein and the hepatic artery, both 
of which bring the blood to the capillaries of adjoining lobules. 
With these interlobular blood vessels are found the bile ducts 
which convey the bile, the secretion of the liver cells, away from 
the bile capillaries (i.e., lumina of tubules) of the adjoining lobules. 
Note that the veins and arteries may be distinguished from each 
other by the character of their walls, the arteries having the thicker 
walls and the lining thrown into folds. Note also that the 
cuboidal epithelial cells lining the bile ducts distinguish them 
from both veins and arteries. Study sections of injected liver to 
corroborate these points. Draw a cross section of a single lobule, 
showing its relation to adjoining lobules , and the arrangement 
of blood vessels and bile ducts associated with it. 

Under high power study the details of liver cells. Note their 
cuboidal form, nucleus and cytoplasm, the latter often exhibiting 
numerous glycogen granules and other non-living structures. The 
bile capillaries which are really the lumina of the gland tubes which 
make up the liver, are distinguishable here and there merely as 
clefts beween the liver cells; the blood capillaries have their own 
lining of flat endothelial cells, and in injected liver, may be seen 
among the gland cells. (Compare with sections of Amphibian 
and reptilian liver in which the cells are larger and the structure 
simpler. Note particularly that in the reptilian liver the tubular 
character of the gland is very evident.) Draw a few adjoining cells 
showing all the details you can make out. 


xvni. THE UROGENITAL SYSTEM 


A. EXTERNAL FORM AND RELATIONSHIPS. 

From demonstration preparations, review the general iden¬ 
tification of the urogenital organs, in situ , in both male and female 
of several species of mammals (cf. pp. 13-15). Draw such details 
of the relationships in each sex as have not previously been recorded. 

1. Urinary (Uropoietic) Organs.- —Kidneys, their location 
(note which is more anterior, cf. man), relation to peritoneum, 
form, blood supply; suprarenal glands, their relation to the kid¬ 
neys; ureters, relation to the kidneys and bladder; bladder, its 
location with reference to other pelvic organs, and to peritoneum 
(folds of which form the ventral suspensory ligament and two 
lateral ligaments), the location of orifices of ureters and urethra, 
the appearance of the walls of the bladder, both in the distended, 
and contracted conditions, the presence of muscular and mucous 
coats (the latter seen by opening the organ); urethra, its short 
course in the female to the external orifice in the urogenital sinus, 
its prolongation and specialization in the male into the organ 
of copulation (the penis), represented in the female by the clitoris. 

2. Female Genital Organs. —Ovaries, their location, relation 
to peritoneum (note that each is enclosed, together with the 
uterine tube and uterus, in a fold of peritoneum known as the 
mesovarium or broad ligament), form, size; uterine tubes (oviducts), 
relation of the funnel-shaped mouth of uterine tube to ovary 
(demonstrate by probing with a wax-tipped bristle), and the coiled 
course of the tube to reach the uterus; uterus, its location with 
reference to other pelvic organs and to peritoneum, its division into 
two lateral cornua and a median body (in the rabbit, two separate 
uteri) leading posteriorly into the vagina, and its thick wall consist¬ 
ing of muscular and mucous coats; vagina, with thinner walls,* 
leading posteriorly to the external orifice dorsal to the urethral 
orifice within the urogenital sinus. Note the mid ventral elevation 
of the wall of the urogenital sinus, known as the clitoris. 


i 3 2 


MAMMALIAN ANATOMY 


3. Male Genital Organs. —Note location of the testes in the 
scrotal sacs and the muscular and peritoneal elements which 
enter into the walls of the latter and enclose the testes themselves. 
The removal of the visceral peritoneal layer discloses the testis 
in its capsule, and its associated structure, the epididymis, the 
tubules of which form the connection between the testis and 
the ductus deferens through which its secretion is discharged. 
Note the course of the ductus deferens through the inguinal canal 
as one component of the spermatic cord. Demonstrate the rela¬ 
tion of the ductus deferentia, seminal vesicles, and prostate and 
bulbourethral glands to each other and to the urethra. The penis 
is characterized by the development of three columns of erectile 
tissue ( i.e ., tissue containing large blood sinuses, which, when 
distended with blood, produce the erect condition necessary to 
copulation) as follows: The median corpus cavernosum urethrae 
in the posterior region, ending in the enlargement known as the 
glans, and the two lateral corpora cavernosa penis, all withdrawn 
distally within the prepuce, when the penis is not in a state of 
erection. Note also certain muscular elements which arise from 
the ischium and are inserted into the penis. 

B. STRUCTURE. 

1. The Kidney. 

Macroscopic Study. —Examine externally a simple kidney such 
as that of a rabbit or guinea pig, carefully removing the loose 
packing of fat and areolar tissue in which it is imbedded. Note 
the tough capsule covering it, and the depression or hilus through 
which the ureter and the renal blood vessels pass. Cut the kidney 
by a longitudinal section passing through the hilus and identify 
the following regions and parts: The granular cortex; the medulla, 
with striated appearance converging from the cortex to the apex 
of a large papilla; the cavity or pelvis into which the papilla 
projects embraced by the expanded funnel-shaped calyx from 
which the ureter leads; and the veins and arteries outside of the 
calyx and ureter, within the sinus of the kidney. Since the ureter, 
calyx, and blood vessels are held together within the sinus by a 
packing of fatty areolar tissue, this must be removed in order to 


THE UROGENITAL SYSTEM 


1 33 


show these structures. Draw a longitudinal section showing the 
plan of structure of a simple kidney. 

For comparison with this simple kidney of the rabbit study 
the compound kidneys (i) of the cow or calf where the components 
are more or less separated, and (2) of the sheep and pig where the 
components are closely fused as in the human kidney. Draw 
a diagram of each type showing the relation of the components. 

Microscopic Study (Lab. SI. Coll.).—The real secreting organs 
of the kidney are the very numerous and complicated renal 
tubules. Each tubule begins with (a) the glomerulus capsule, 
which consists of a spherical expansion rendered two layered 
by the pushing in of one side through the ingrowth of a knot of 
blood vessels (a glomerulus). These are distributed through the 
cortex and form the renal corpuscles. From this capsule leads 
( h ) the convoluted tubule, situated also in the cortex, and leading 
into ( c ) the straight tubule, which forms a loop, consisting of a 
thinner walled descending and a thicker walled ascending region, 
extending into the medulla and back into the cortex, where it 
leads into (d) the intercalated piece, a second convoluted region, 
which leads into (e) a collecting tubule, into which many other renal 
tubules open; this passes through the medulla to reach (/) a pap¬ 
illary duct which opens upon the free surface of the papilla by a 
pore through which the secretion (urine) is constantly drained off 
into the calyx, to be carried from the kidney through the ureter. 

Study under low power a section of rabbit kidney. Identify 
the cortical and medullary regions, and note the general course of 
the tubules in each. Draw the whole section to show its general 
topography as seen under low power. 

Study under high power each region to identify (1) the cap¬ 
sules of the glomeruli with the lining of flat epithelial cells and the 
beginning of the convoluted tubule, and (2) sections of various 
regions of the renal tubules. Draw details , showing characteristic 
form of the epithelial cells of as many regions as you are able to 
identify (cf. illustrations and description in any good text-book of 
histology). 

Study for comparison, sections of the kidneys of other mam¬ 
mals, including man, also sections of injected kidney, noting that 
the knot of blood vessels of a glomerulus is not a true capillary 


134 


MAMMALIAN ANATOMY 


since the efferent vessel continues as an arteriole to finally break up 
into the capillary network of the kidney. 

2. The Ovary (Lab. SI. Coll.). 

Study either macroscopically or with the aid of a dissecting 
microscope, slides showing sections through the ovary of the cat, 
rabbit, or other mammal. Note the general shape and appear¬ 
ance of the section and the location of the hilus (the region of 
attachment to the body wall and of entrance and exit of blood 
vessels and nerves). 

Examine under low power of the compound microscope and 
identify (a) the vascular supporting framework or stroma, of 
a richly cellular connective tissue, which radiates from the hilus 
toward the periphery between certain large oval structures, the 
vesicular ovarian follicles (Graafian follicles); ( b ) the peripheral 
region or cortex, in which are located the various early stages of the 
developing germ cells (ova), each enclosed within a follicle which 
consists of one or more layers of cells; (c) the germinal epithelium 
(often injured in making the preparations), which consists of a 
single layer of epithelial cells covering the surface of the ovary; 
and ( d ), in ovaries of sexually mature animals, larger or smaller 
homogeneous areas each of which is a section through a corpus 
luteum, the structure which for a time occupies the space left by 
the rupture of a mature follicle to discharge the ovum from the 
surface of the ovary. Draw a view of the whole section showing the 
general topography. 

Under low and high power study various stages in the develop¬ 
ment of the ovarian follicles as follows: 

(a) A primary ovarian follicle (young material is necessary for 
this): This consists of a group of cells which has sunk into the 
stroma from the germinal epithelium; one cell of the group devel¬ 
ops into the germ cell (the ovum), the others arrange themselves 
in a single layer about the ovum and form the nutritive layer 
known as the follicular epithelium. Draw a section through a 
typical primary follicle , showing the cell arrangement. 

( b) A vesicular ovarian follicle: This consists of (i) an outer 
covering developed from the stroma and known as the theca 
folliculi, (2) several layers of follicular epithelial cells lining the 


THE UROGENITAL SYSTEM 


135 


follicle and forming the stratum granulosum, (3) a thickened mass 
of follicular epithelial cells surrounding the ovum and forming the 
cumulus oophorus, and (4) a fluid, the liquor folliculi, which fills 
the cavity of the follicle and becomes finally very great in amount 
(to serve the mechanical function of carrying out the ovum when 
the follicle ruptures). 

Select with care a good section through an ovum in a large 
follicle, and study the ovum to identify (a) the cell membrane or 
zona pellucida, ( b ) the cytoplasm containing yolk (small in 
amount in the mammals) and constituting the vitellus, (c) the 
nucleus, known as the germinal vesicle, and ( d ) the nucleolus, 
known as the germinal spot. Draw a typical section through a 
large follicle , showing its parts and the parts of the ovum. 

3. The Testis (Lab. SI. Coll.). 

Study under the low power of the compound microscope, 
transverse sections of the mammalian testis, stained by some 
method which will bring out cells in mitosis. Note that the 
section consists of a large number of smaller sections, mainly 
transverse, of the numerous seminiferous tubules of which the 
testis is chiefly made up while there is also a small amount of 
intertubular connective tissue in which are present large cells 
known as the interstitial cells. In the walls of the tubules all 
stages of developing male germ cells may be seen. Carefully select 
for study under high power sections of different tubules which show 
the following stages of development of the male germ cells, 
noting particularly which of these stages occur simultaneously 
in a given tubule: 

(a) Spermatogonia, the small cells which lie in contact with the 
basement membrane of connective tissue forming the outer wall of 
the tubule. 

( b ) Primary spermatocytes, formed by the growth of certain of 
the spermatogonia. 

(c) Secondary spermatocytes, formed by the division of each of 
the primary spermatocytes into two daughter cells; they are there¬ 
fore half the size of the primary spermatocytes and twice as 


numerous. 


i3 6 


MAMMALIAN ANATOMY 


( d ) Spermatids, formed by the division of the secondary 
spermatocytes; they are half the size of the latter and twice as 
numerous, and lie almost or quite detached in the lumen of the 
tubule until they begin to elongate and reach in clusters between 
the columns of spermatogonia and spermatocytes in the wall of the 
tubule, and attach themselves to certain large pyramidal nutritive 
cells which lie on the basement membrane and are known as 
the Sertoli cells. These support and nourish the spermatids 
during their transformation into spermatozoa. 

(e) Spermatozoa, the fully developed male germ cells; these are 
greatly elongated, motile cells with lance-shaped heads (in the rat) 
in which the nucleus is located, and a long filamentous tail which 
serves as the organ of locomotion, by means of which the cells 
move freely in the tubules and the ducts. (Cf. living spermatozoa 
of rat, guinea pig, or some amphibian, and demonstration slides 
showing human or other spermatozoa.) 

Draw details of various tubules to show as many as possible of the 
stages in the growth and development of the male germ cells. 


XIX. THE DEVELOPMENT OF MAMMALS 


A. DEMONSTRATION OF THE GRAVID UTERUS IN 

RODENTS AND CARNIVORES. 

i» General Examination (guinea pig, rabbit, cat, preferably 
fresh specimens).—Note the greatly enlarged veins and arteries 
indicating a corresponding increased blood supply; the number of 
embryos present, their size, and their location in the uterus. 
Draw a view of the uterus showing the number and location of the 
embryos. 

2. Extraembryonal Structures and Their Relation to the 
Embryo. —After carefully opening the uterus in the region of one 
of the embryos, identify (a) the chorion, a sac which encloses the 
embryo and is closely applied to the lining of the uterus, from 
which it can, however, be separated in most cases, in toto; ( b ) the 
placenta, either discoiclal or zonary, a vascular structure attached 
to the inner wall of the uterus, formed in part from its lining 
mucous membrane and in part from a differentiated region of the 
chorion, and hence supplied with two sets of blood channels, one 
connected with the maternal and the other with the embryonal 
circulatory system, (c) the umbilical cord passing from the pla¬ 
centa to the embryo and containing the veins and arteries which 
connect the placenta with the circulatory system of the embryo, 
and (d) the amnion, a thin transparent membrane which forms a 
sac enclosing the embryo and containing the amniotic fluid. 
Draw one or more diagrams showing the relation of the embryo to the 
extraembryonal parts. 

B. DEMONSTRATION OF LACTATION. 

In the various specimens of the gravid female guinea pigs 
studied note the condition of the mammary glands, and their 
increasing size with the advance of pregnancy. Examine a fresh 
dissection of a specimen in lactation (after the birth of the young) 
and demonstrate by an incision into the gland tissue, the presence 

i37 


i3» 


MAMMALIAN ANATOMY 


of an abundance of secretion (milk) in the gland. Note also the 
enlarged condition of the nipples in which the gland orifices are 
located. 

C. DEVELOPMENTAL STAGES. 

By means of the dissecting microscope, study a series of stages 
of mammalian embryos (mouse, rat, cat, or pig) and follow out the 
development of trunk, head, limbs, and viscera (exposed by 
previous dissection). Draw three stages each magnified five 
diameters. 

D. DEMONSTRATION PREPARATIONS OF HUMAN (OR 

OTHER PRIMATE) MATERIAL. 

1. Reproductive system with gravid uterus laid open to show 
the discoidal placenta, the amnion (closely adherent to the chorion), 
and the long twisted umbilical cord extending from the placenta 
to the embryo. Draw. 

2. Chorion of early human embryo before the development of 
the placenta, showing chorionic villi. Draw. 

3. Various stages of human embryos showing changes of form 
and proportions during development. (Cf. other mammalian 
embryos, and various atlases of human and mammalian embry¬ 
ology.) Identify any extraembryonal parts which may be 
attached to these specimens. Draw any which illustrate points 
not already recorded. 


SUMMARY OF EQUIPMENT AND MATERIAL 

I. MANIKINS AND MODELS. 

At least one good life-size anatomical manikin, capable of as 
complete dissection as possible. (The best available are probably 
those manufactured by Montandon, the successor of Auzoux.) 

The Suzuki black-board manikin (of Japanese manufacture, 
cf. footnote p. i, for superficial anatomy). 

Model of dissected torso (human), life size, preferably one of 
each sex, for use in the laboratory for the demonstration of the 
thoracic and abdominal viscera. 

Small plaster muscle casts of the whole figure in various poses 
(e.g.j the Houdon muscle figure). These are inexpensive and are 
very convenient for demonstration in the laboratory to small 
groups of students, and for practice in recognizing superficial 
bony landmarks and muscles. 

Models of the human brain, natural size and capable of dissection. 

Enlarged models of the human brain showing relations of 
fiber tracts (that of Dr. Florence Sabin is to be particularly 
recommended). 

Various models of lower vertebrate brains. 

Models of the human head showing sagittal sections, and 
topographical relations of the pharynx. 

Model, enlarged, of the human larynx and its various parts. 

Model of the human eye and its surroundings, enlarged. 

Model of the human ear, enlarged, showing details of labyrinth. 

Models of male and female pelves, the latter with gravid uterus 
and several stages of embryos. 

Miscellaneous models showing such structures as the detailed 
musculature of various parts, the articulations of bones, or the 
enlarged details of structure of various organs of the body. 

II. SKELETONS, AND SKELETAL PREPARATIONS. 

At least two correctly mounted human skeletons, one male, the 
other female. 


i39 


140 


MAMMALIAN ANATOMY 


One complete disarticulated human skeleton for each group 
of from two to four students in a laboratory division. 

Additional skulls sufficient to supply each student in a labora¬ 
tory division with one. About half of these should be sawn 
horizontally and at least one or two sagittally. Each skull 
should always be accompanied by, and handled upon, a small 
cushion (about io inches square) half filled with bran, which not 
only saves much wear and tear of the skull but also supports it 
firmly in any desired position. 

One or more completely disarticulated human skulls, either 
mounted or unmounted. 

A series of human skulls of different ages from birth to senility. 

Preparations showing the natural ligaments of various articu¬ 
lations of the human skeleton. 

A preparation of the human skull showing the course of the 
cranial nerves to the various parts of the head. 

Mounted skeletons of other mammals, such as the rabbit, cat, 
sheep, and several species of monkeys, including at least one 
higher anthropoid. 

Skeletonized anterior and posterior appendages of the rabbit, 
pig (and as many other ungulates as possible). These may be 
student preparations which each class may add to for the benefit 
of the next class (cf. p. 52). 

Separate bones, and fragments of bones, of as large a variety 
of mammals as possible, including man. 

III. DEMONSTRATION DISSECTIONS OF A MORE OR 
LESS PERMANENT NATURE. 

(Most of these may be made in the laboratory and may be 
kept and used from year to year with occasional renewal and 
additions.) 

' 1 

Transverse sections through the middle of the trunk region 
of the dog fish. 

Median sagittal and transverse sections through whole bodies 
of small mammals or advanced embryos. 

Dissections of young cats or kittens to show the brain and 
spinal cord with the roots and divisions of the spinal nerves 
in situ. 


SUMMARY OF EQUIPMENT AND MATERIAL 141 

Dissections of cats or other mammals to show the brachial 
and lumbosacral plexuses in situ. 

Dissections of cats or other mammals to show the chain 
sympathetic ganglia and their connections with the visceral 
divisions of the spinal nerves. 

Dissections showing the brain of the dogfish, and of other 
vertebrates, particularly the more primitive classes in situ. 

Dissections of cats or other mammals with circulatory system, 
injected, for comparison with those forms used in the laboratory, 
or as a substitute (if time is limited) for specimens injected by 
individual students. 

Dissections of cats, rabbits, or other mammals to show the 
relationships of the various parts of the digestive system. 

Dissections of cats and rabbits to show the urogenital systems 
of males and females of each species. 

Preparations of gravid uteri, preferably of some Primate. 

Sets of mammalian embryos of various stages (pig embryos are 
readily obtainable), for the study of the development of external 
form. 

A series of human embryos of different stages, some, at least, 
with the placenta and other extraembryonal parts attached. 

Miscellaneous preparations, especially of parts of the human 
anatomy, such as dissections of the tongue and larynx, heart, 
etc. 

IV. SLIDE COLLECTIONS. 

Sets of slides (laboratory slide collection) in sufficient numbers 
to supply individual students of a laboratory division. The 
following are suggested as desirable: 

A. Mitosis in tissue cells. 

1. Growing tips of onion root, longitudinal sections, stained 

with iron haematoxylin. 

2. Epidermis of salamander, surface mount, conjunctiva of 

eye, stained in haematoxylin or safranin. 

B. Epithelial tissues. 

1. Simple epithelium. 

(a) Cuboidal: sections of gall bladder of Necturus. 


142 


MAMMALIAN ANATOMY 


( b ) Columnar: (i) Transverse sections of the stomach 

and gastric diverticula of a grasshopper; (2) Trans¬ 
verse sections through some simple type of vertebrate 
intestine; (3) Sections through the mammalian 
oviduct. 

(c) Squamous: Surface mounts of the mesentery. (Cf. 

also serosa in the transverse sections of vertebrate 
intestine.) 

2. Stratified epithelium: 

(a) Cuboidal: Sections of larval amphibian skin. 

( b ) Columnar: Sections of oesophagus of lungless sala¬ 

mander (Desmognathus, Eurycea). 

(c) Squamous: (1) Sections of adult amphibian skin, 

unpigmented region (Desmognathus, Eurycea) show¬ 
ing also simple alveolar glands; (2) Surface mounts of 
moult layer of adult amphibian skin; (3) Sections 
of human fetal skin; (4) Sections of lining of mouth 
of some mammal; (5) Sections through mammalian 
oesophagus. 


C. Skeletal tissues. 

0 

1. Tensile varieties. 

(a) Loose: (1) Use sections of various organs such as 
intestine; (2) Adipose tissue of mesentery, surface 
mounts of thin regions. 

(. b ) Dense: (1) Longitudinal and transverse sections of 
tendons; (2) Teased preparations, longitudinal, and 
transverse sections of elastic ligament (ligamentum 
nuchae). 

2. Rigid varieties. 

(а) Cartilage: (1) Sections of hyalin cartilage; (2) Sections 
of elastic cartilage; (3) Sections of fibro cartilage. 

(б) Bone: (1) Transverse sections through the decalcified 
shaft of a long bone; (2) Transverse sections of dry human 
bone (shaft of long bone); (3) Longitudinal sections of dry 
human bone (shaft of long bone); (4) Longitudinal sec¬ 
tions of growing bone (end of a long bone). 


SUMMARY OF EQUIPMENT AND MATERIAL 143 

D. Muscle tissues. 

1. Smooth involuntary muscle: Teased preparations (Use 

also sections of intestine for longitudinal and transverse 
sections of smooth muscle in situ.) 

2. Striated voluntary muscle. 

(a) Teased preparations. 

(b) Longitudinal and transverse sections of voluntary 

muscle of Necturus. 

(c) Longitudinal and transverse sections of voluntary mus¬ 

cle of rabbit or other mammal. 

3. Striated involuntary, or heart, muscle: Longitudinal sections 

through a piece of heart muscle. 

E. Nerve tissues. 

1. Cells. 

(a) Smear preparations of nerve cells of spinal cord. 

(■ b ) Golgi preparations of cerebral and cerebellar cortex. 

(c) Sections through cerebral and cerebellar cortex to show 
details of structure of the various types of cells in situ. 

2. Fibers. 

(a) Teased preparations of nerve fibers stained in haema- 

toxylin. 

(b) Teased preparations of nerve fibers treated with osmic 

acid. 

(c) Transverse sections of nerve fibers stained with haema- 

toxylin. 

( d ) Transverse sections of nerve fibers treated with osmic 

acid. 

3. Nerve endings. 

(a) Motor end plates in voluntary muscle. 

(b) Sensory endings (spindles) in voluntary muscle. 

(c) Pacinian corpuscles (in pancreas of cat). 

(d) Taste buds in the foliate papillae of the rabbit. 

(e) Preparations showing the olfactory and epithelial 

cells of the nasal mucous membrane. 

(f) Sections of the retina (frog, rabbit, or other form). 

(g) Sections through the spiral organ of Corti (ear of pig, or 

other mammal). 


144 


MAMMALIAN ANATOMY 


F. Organs. 

1. Transverse sections of spinal cord. 

2. Sections of injected tissues and organs for the study of 

capillaries (e.g., intestine, tongue, lung). 

3. Transverse sections through arteries and veins. 

4. Transverse sections of the intestine of Necturus. 

5. Transverse section of mammalian intestine (rodent recom¬ 

mended). 

6. Longitudinal sections through mammalian intestine (car¬ 

nivore recommended). 

7. Sections through the various regions of the wall of the 

stomach. 

8. Sections through the salivary gland (or the pancreas). 

9. Sections of liver (pig and cat). 

10. Sections of Necturus liver. 

11. Sections of simple (rabbit) kidney. 

12. Sections of compound kidney (man). 

13. Sections of young and of mature mammalian ovaries. 

14. Sections of mammalian testis. 


G. Blood. 

Smear preparations of human blood stained with Wright’s 
stain. 

Specially selected slides (demonstration slide collection), 
to be accompanied by suitable references or descriptions, and 
usually arranged under the microscope by the teacher or 
demonstrator. 

A. Examples of types of cells from various tissues, showing cell 

differentiation. 

B. Examples showing details of mitosis. (Ascaris eggs are 

especially good.) 

C. Special preparations of different tissues and organs for finer 

details of structure. 

D. Sections through various organs which are not otherwise made 

objects for histological study. 


SUMMARY OF EQUIPMENT AND MATERIAL 


!45 


V. APPARATUS AND INSTRUMENTS. 

A dissecting and a compound microscope for each student in a 
laboratory division. 

A set of dissecting instruments (including fine pointed and 
heavy forceps, a strong pair of scissors, and at least two scalpels of 
different sizes) for each student. 

A supply of water hones for sharpening scalpels. 

A medium hard (2H or 4H) drawing pencil, eraser, and large 
note book (10 X 14 inches) of good smooth quality, but not 
too heavy paper, for each student. 

A supply of small hand saws, chisels, wooden mallets, and 
bone forceps, and special knives, sufficient for each student or 
each two students in a laboratory division. 

Some form of manifolding apparatus. 

Small protractors for measuring the angles of bones. 

Several long thin knives for sectioning brains. 

Several hand section cutters. 

At least one good microtome, and extra microtome knives. 

At least one large (1000 c.c.) and one small (100 c.c.) glass 
graduate. 

Small glass medical (male urethral) syringes for the injection of 
circulatory systems. (These, when connected by short pieces 
of rubber tubing with cannulas made by drawing out small glass 
tubing, are most satisfactory for injection of blood vessels.) 

A paraffine oven or other device for imbedding (cf. p. 24). 

An optical model of the eye (the simple one manufactured by 
the Harvard Apparatus Company, is recommended). 

Some form of stethoscope. 

Some form of sphygmograph. 

Some form of sphygmomanometer. 

Some form of haemocytometer. 

Some form of haemoglobinometer. 

An hydrometer (for fluids heavier than water). 

A centrifuge machine (of the type used for examination of 
milk). 

A circulation scheme for study of the mechanical principles of 
circulation (the one devised by Porter, and furnished by the 

Harvard Apparatus Company, has been found very satisfactory). 

10 


146 


MAMMALIAN ANATOMY 


A respiration scheme for the study of the mechanical principles 
of respiration (devised by Porter and furnished by the Harvard 
Apparatus Company). 

A pneumograph, writing tambour, and kymograph (Harvard 
Apparatus Company). 

A spirometer. 

Measuring tapes. 

Large anthropological calipers (technically known as the 
pelvimeter). 

An anthropometer. 

Access to an incubator. 

VI. MISCELLANEOUS EQUIPMENT. 

Large tubs or tanks with tight covers for the preservation of 
class material, of some material ( e.g ., glass, enamel, or papier 
mache) which will not be corroded by bichloride of mercury. 

An ample supply of double crystallizing dishes, about 8-10 
inches in diameter, and 3-4 inches deep, of heavy glass, one of 
which may be used as the cover for the other in the preservation 
of individual student material (such as brains), while either dish 
may be used as a temporary container for material which 
should be studied under water. 

A supply of some form of modeling clay, e.g., plastilina. 

An ample supply of small glass phials for the handling of 
histological material. 

A supply of small glass tubing and rubber tubing to fit it. 

Microscope slides, cover-slips, watch crystals, pipettes, and 
slide labels. 

Absorbent cotton, filter paper, pure tissue paper for cleaning 
lenses, absorbent gauze for cleaning slides and cover-slips, an 
abundant supply of coarse unbleached cheese cloth for wrapping 
material for preservation, heavy manilla tags for labeling material. 

Sets of reagent bottles, small dropping bottles, staining jars, 
balsam jars, and alcohol lamps. 

General reagents: Formalin (40% formaldehyde); 95% alcohol 
(for all except histological purposes, denatured alcohol may be 
used if more convenient); corrosive sublimate in the form of large 
crystals (a tank or tub of saturated solution of corrosive sublimate 


SUMMARY OF EQUIPMENT AND MATERIAL 147 

may be kept constantly ready for use by the simple device of 
suspending from the top a cheese cloth bag containing crystals of 
the sublimate). Absolute alcohol or acetone; xylol or turpentine; 
paraffine (the commercial “parawax” for household use proves 
of excellent quality for ordinary imbedding, and is inexpensive); 
albumen fixative; Canada balsam; iodine (in an aqueous solution 
of potassium iodide); methylene blue (aqueous solution); haema- 
toxylin; eosin (in aqueous or alcoholic solution); Wright’s stain 
for blood; glacial acetic acid; glycerine. For injection of blood 
vessels, pure gelatine (in thin sheets), corn starch, and various 
dry pigments in fine powdered form such as are used by house 
painters. 

VII. FRESH MATERIAL. 

One full-grown guinea pig (or other small mammal) for each 
student (or two students) for the general study of viscera. 

One full-grown rabbit for each two (or four) students, to be 
hardened and preserved for the study of muscles. Certain of 
these may be used first for the demonstration of the general distri¬ 
bution of muscles, and then preserved for later dissection. 

One pig’s foot (anterior or posterior) for each student (or 
each two students). 

One head of sheep or calf for each student (or for each two 
students). 

One fresh mammalian eye for each student. 

Several short lengths of spinal cord (lamb, calf, pig, or cat), 
preferably from different regions, hardened and preserved for 
macroscopic study, for each laboratory division of twelve students. 

One set of thoracic viscera (“plucks”) for each two students; 
these should have the trachea, larynx, and tongue attached, and 
at least one in each laboratory division should have the entire 
liver, and as much as possible of the diaphragm. 

One cat, rabbit, or other mammal for each student (or each two 
students) for injection of blood vessels. These may be preserved 
and dissected later. 

One or more intestinal tracts of cat for each laboratory division 
of twelve students, to be hardened and preserved and cut into 
short lengths for the macroscopic study of the alimentary canal. 


148 


MAMMALIAN ANATOMY 


One simple kidney (rabbit, or guinea pig) for each student. 
These may be removed from specimens used for other purposes 
and preserved until needed. 

One beef (veal), and one pig or sheep (lamb) kidney for each 
small group of students. 

Several gravid females of various species of mammals, for 
demonstration of the uterus and embryo, with the relation of 
extraembryonal parts. 

Occasional specimens of Necturus, small salamanders, frogs, 
rats, guinea pigs, rabbits, and cats for demonstrations, or for 
material for histological study; also occasional small supplies of 
fresh material for histological study from the market or abattoir. 

VIII. BOOKS. 

Among the numerous excellent, well-known text and reference 
books of human and comparative anatomy, histology, physiology, 
and embryology, with which every laboratory is presumably 
equipped, the following books may be mentioned as of particular 
value in connection with the course here outlined: 

Bass and Johns, Laboratory Diagnosis. Rebman, New York. 

Beddard, Edkins, Hill, Macleod, and Pembrey, Practical 
Physiology. Arnold, London. 

Brubaker, A Textbook of Human Physiology. Blakiston, 
Philadelphia. 

Chauveau (English translation by Fleming), The Comparative 
Anatomy of the Domesticated Animals. Appleton, New York. 

Dahlgren and Kepner, Principles of Animal Histology. Mac¬ 
millan, New York. 

Davison, Elements of Mammalian Anatomy, with especial 
reference to the Cat. Blakiston, Philadelphia. 

Ellenberger and Giinther, Histologie der Haussaugertiere. 

/ 

Parey, Berlin. 

Fiske, An Elementary Study of the Brain, based on the dissec¬ 
tion of the brain of the Sheep. Macmillan, New York. 

Flower, Osteology of Mammalia, Macmillan, New York. 

Guyer, Animal Micrology. University Press, Chicago. 

Hardesty, Neurological Technic. University Press, Chicago. 

His, Anatomie Menschlicher Embryonen. 


SUMMARY OF EQUIPMENT Al^D MATERIAL 


149 


Jordan and Ferguson, Textbook of Histology. Appleton, 
New York and London. 

Kollmann, Handatlas der Entwicklungsgeschichte des Mens- 
chen. Fischer, Jena. 

Minot, Laboratory Text-book of Embryology. Blakiston, 
Philadelphia. 

Morris and McMurrich, Human Anatomy. Blakiston, 
Philadelphia. 

Piersol, Human Anatomy. Lippincott, Philadelphia and 
London. 

Porter, An introduction to Physiology. Lippincott, Phila¬ 
delphia and London. 

Radasch, Manual of Anatomy. Saunders, Philadelphia and 
London. 

Sabin, An Atlas of the Medulla and Midbrain. Friedenwald, 
Baltimore. 

Santee, Anatomy of the Brain and Spinal Cord. Blakiston, 
Philadelphia. 

Schneider, Lehrbuch der Vergleichenden Histologie der Tiere. 
Fischer, Jena. 

Sisson, Veterinary Anatomy. Saunders, Philadelphia. 

Sobotta and McMurrich, Atlas and Textbook of Human 
Anatomy. Saunders, Philadelphia and London. 

Szymonowicz (English translation by MacCallum), A Text¬ 
book of Histology and Microscopic Anatomy of the Human Body. 
Lea, Philadelphia and New York. 









































INDEX 


Abdominal cavity, contents of, 8, 9, 
11-13 

Acidophiles, 116 

Alimentary canal, n-13, 124, 125 
histology of, 126, 128 
Alveolar type of gland, 128, 129 
Amnion, 137 

Anterior appendage, muscles of, 6 , 53-55 
skeleton of, 3, 45, 46 
Apparatus required, enumeration of, 
I4S-I47 

Appendages, 46 

muscles of, 6, 53-58 
skeleton of, 3, 45-48 
Appendicular skeleton, 3, 45-48 
Aquaeductus cerebri (aqueduct of the 
cerebrum), 72, 79, 84 
Arachnoid, 74, 76 
Areolar tissue, histology of, 34, 35 
Arteries, gross anatomy of, 106-109 
histology of, 109 
injection of, 104-106 
superficial, location of in living, 101 
Articulations, general study of, 48, 49 
vertebral, 40 
Atlas, 41 

Auditory ossicles, 44, 93 
Axial skeleton, 2, 3 

Basophiles, 116 

Bichloride of mercury method for 
preservation of material (see 
also Corrosive Sublimate), 52 
Bladder, 9, 14, 131 
gall, 13, 29 
urinary, 9, 14, 131 
Blood, 113-118 

cells, 21, 113-116 
coagulation of, 116, 117 
histology of, 113-116 
movement of, 110-112 
properties of, 116-118 


Blood vessels, 102-112 

dissection of, 106-109 
histology of, 109 
injection of, 102-106 
Body cavity, 3 
Bone, 36 

histology of, 36-38 
Books, list of, 148, 149 
Brain, cavities of (see also Ventricles), 79 
directions for removing, 74, 75 
dogfish, 71, 72 

external features of, 56, 60-64, 71, 
75-78 

fluid for preserving (formalin- 
alcohol), 75 

internal structure of, 78-85 
mammalian, 11, 58-70, 73-85 
median sagittal section of, 71, 72, 80 
stem, dissection of, 83, 84 
ventricles of, 71, 72, 79 
Bronchi, 97, 98 
Bulbourethral gland, 132 

Caecum, 13, 125 
Canalis centralis, 68, 79, 84 
Capillaries, 109 
Carpus, 3, 32, 46 
Cartilage, 32, 35, 36 
Cartilages of larynx, 98, 99 
Cavities of body, 7 

of brain (see also Ventricles), 79 
outlined by skeleton, 3 
Cavum tympani, 93 
Cell division, 28 
Cells, blood, 21, 113-116 

epithelial, 20, 21, 27-30, 127-130 
fiver, 21, 128 
muscle, 27, 50, 51 
nerve, 27, 59, 60 
plant, 21, 22 
secretary, 127-130 
skeletal, 27 

151 


I 5 2 


INDEX 


Cells, types of, 20-22 
Cerebellum, 71, 72, 77, 82-84 
dissection of, 82, 83 
histology of, 60 
Cerebrum, 75-77 
histology of, 60 
hemispheres, 71, 75-77, 80 
dissection of, 80-82 
peduncles (see Pedunculi cerebri) 
Cervical vertebrae, 2, 41 
Chiasma, optic, 77, 80 
Chorion, 137 
Chyle, 126 

Circulation scheme (of Porter), in 
Clavicle, 3, 45 
Clearing of tissues, 24 
Clitoris, 131 

Coagulation of blood, 116, 117 
Coccyx, 2, 41 
Coelom, 3, 8 
Coelomic cavity, 8-11 
Colon, 13, 125 
Commissures of brain, 8c 
of spinal cord, 70 

Compound microscope, directions for 
use of, 17-19 

Connective tissue, 31, 32 

embryonic, cells of, 27, 30 
histology of, 34 35 

Contents of cavities of the body, 7-11 
Corona radiata, 83 
Corpora quadrigemina, 76, 84 
Corpus callosum, 76, 79, 80, 81 

striatum (or Corpora striata), 71, 
81-83 

Corrosive sublimate method for pre¬ 
serving material, 52 
Cortex, cerebellar, 60 
cerebral, 80, 81 
Corti, spiral organ of, 65 
Cranial cavity, 3 

floor of, 43, 44, 86, 87 

nerves, foramina of exit of, 43, 87 

roots of, 78 

Decalcification, 23 
Dehydration of tissues, 24 
Demonstration dissections, list of, 140, 
141 

slide collection (Dem. SI. Coll.), 
27 (note), 144 


Diaphragm, 8, 9, 13, 96 
Diencephalon, 71, 72, 76, 77, 79, 82-84 
Digestive glands, histology of, 128-130 
system, 11-13, 124-130 
gross anatomy of, 124-12 5 
histology of, 126-128 
physiological demonstrations, 
126 

tract (see Alimentary canal) 
Dissecting, directions for muscles, 52 
general directions for, 8-15 
Dogfish, brain of, 71, 72 
Drawings, directions for, 7, 8 
Ductus deferens, 15, 132 
Duodenum, 13, 125 
Dura mater, 66, 67, 74, 86, 87 

Ear, 92-94 

external, 92, 93 
internal, 92-94 

middle (see also Cavum tympani), 
93 

Elastic cartilage, 36 
tissue, 35 

Embryos, human, 138 

mammalian, 9 (note), 137, 138 
Epidermis, 22, 29, 30, 31 
Epididymis, 132 

Epiphysis (see also Pineal body), 71, 72, 
76, 83, 84 
Epistropheus, 41 

Epithelial cells, 20, 21, 27, 28-30, 127, 
133 

tissue, 28-30 

Epithelium, 28-30, 127, 128 
follicular, 134 
germinal, 134 

Equipment, miscellaneous, 146, 147 
Erythrocyte (see also Red blood cells), 

113-115 

Expired air, nature of, 123 
Eye, 87-91 

in living subject, 90, 91 
Eyeball, dissection of, 88, 90 
muscles of, 88, 89 

Fascia, 5 

Fasciculi of spinal cord, 70 
Fauces, 86 
Fibro-cartilage, 36 
Fibula, 3, 48 


INDEX 


*53 


Floor of cranial cavity, 43, 44, 86, 87 
of mouth, 94, 95 
Focusing, 18 

Follicle, ovarian, 134, 135 
Follicular epithelium, 134 
Foot, skeleton of, 48 

of pig, dissection of, 32, 33 
Foramen interventriculare, 72, 79, 82 
Forebrain (see Cerebrum) 

Fornix, 79, 80, 82 
Fourth ventricle, 72, 79, 84 
Free limb, anterior, skeleton of, 3, 45, 46 
posterior, skeleton of, 3, 47, 48 
Fresh material, enumeration of, 147, 148 
Frozen sections, 15 
Funiculi of spinal cord, 69 

Ganglia, spinal, 66 
sympathetic, 67 

Ganglion, semilunar (or Gasserian), 87 
Gelatine injection mass, 102, 103 
Genital organs, female, 14, 131 
male, 15, 132 
Girdle, pectoral, 3 
pelvic, 3 

Gland (or Glands), alveolar type, 128,129 
bulbourethral, 132 
cells (see also Secretory cells), 21, 
128, 130 

intestinal, 127, 128 
lacrimal, 88 
lymphatic, n 
mammary, 137, 138 
method of formation of, 128, 129 
peptic, 128 
prostate, 132 
pyloric, 128 
salivary, 11, 134, 129 
suprarenal, 131 
thymus, 10 
thyreoid, n, 98, 99 
tubular type, 127-130 
Glandular masses of neck, 10, n 
Graafian follicle (see Ovarian follicle) 
Gravid uterus, 137, 138 
Gray substance of spinal cord, 69 
Growing bone, histology of, 37, 38 

Haematocytometer, 116 
Haemoglobinometer, 118 


Hand, skeleton of, 46 
Head, topography of, 86 
Heart, 9, 10 

dissection of, 100, 101 
physiological demonstrations, 101 
Hippocampus, 82 

Histological technic, acetic acid treat¬ 
ment for areolar tissue, 34 
clearing, 24 
dehydrating, 24 
fresh material, 19-22 
imbedding, 24, 25 
killing and fixing, 22, 23 
mounting, areolar tissue, 34 
fresh blood, 21, 113, 114 
liver cells, 21 

muscle cells and fibers, 50, 51 
sections on slide, 26, 27 
squamous epithelium, 20 
paraffine bath, 24 (note) 
sectioning, 25 

smear preparations of blood, 114, 

115 

of nerve cells, 59 
spreading sections, 25, 26 
staining, sections on slide, 26, 27 
smears on coverslip, 59, 113-115 
under coverslip, 20 
with hsematoxylin, 26 
with iodine, 21,22 
with methylene blue, 20, 21, 34, 
5G 59 

with Wright’s stain, 114 
teased preparations, 21, 35, 50, 51, 
61, 83, 84 

Histology, of alimentary canal, 126-128 
of areolar tissue, 34, 35 
of arteries, 109 
of blood, 113-116 
of blood vessels, 109 
of bone, 36-38 
of cerebellar cortex, 60 
of cerebral cortex, 60 
of connective tissues, 34, 35 
of digestive glands, 128-130 
of digestive system, 126-130 
of epithelial tissue, 27, 28 
of growing bone, 37, 38 
of intestine, 127, 128 
of involuntary muscle, 50 


I 54 


INDEX 


Histology, of kidney, 133 

of ligamentum nuchae, 35 
of liver, 129, 130 
of muscle tissues, 50, 51 
of nerve tissues, 59-65 
of ovary, 134-135 
of salivary glands, 129 
of skeletal tissues, 34-38 
of spinal cord, 69, 70 
of stomach, 128 
of striated muscle, 50, 51 
of tendon, 35 
of testis, 135, 136 
of unstriated muscle, 50 
of veins, 109 

of voluntary muscle, 50, 51 
Humerus, 3, 45, 46 
Hyaline cartilage, 35, 36 
Hyoid bone, 45, 95, 98 
Hypophysis, 72, 77, 86 

Ilium, 46, 47 
Imbedding, 24 25 
Infundibulum, 72, 77 
Injection mass, gelatine, 102, 103 
of blood vessels, 102-106 
Innominate bone (ossa coxae), 46 
Instruments, list of, 145, 146 
Intestine, 8, 12, 125 

histology of, 127, 128 
Involuntary muscle, histology of, 50 
Iodine, staining with, 21, 22 
Ischium, 47 

Joint structures, 32, 33 

Kidney (or kidneys), 14, 132, 133 
histology of, 133 
structure of, 132, 133 
Killing and fixing of tissues, 22, 23 

Laboratory slide collection (Lab. SI. 

Coll.), 28 (note), 141-144 
Labyrinth, 92-94 
Lactation, 137, 138 
Lacteals, 126 
Large intestine, 13, 125 
Laryngeal cartilages, 98-100 
muscles, 98-100 
Larynx, n, 12, 96, 98-100 
Lateral ventricles of brain, 79-84 


Leucocytes, 113-116 
Ligamentum nuchae, histology of, 35 
Liver, 8, 13, 96, 129, 130 
cells, 21, 129, 130 
histology of, 129, 130 
Living, cardiac sounds in, 101 
interior of mouth of, 94 
location of lungs in, 119 

of superficial blood vessels in, no 
of superficial muscles in, 6, 7 
of superficial skeletal parts in, 3, 
4 

pneumograph record of, 121 
pulse tracings in, m 
respiratory movements of, 119-121 
sounds in, 122 
study of eye in, 90, 91 
Lumbar vertebrae, 2, 41 
Lung, 9, 10, 96-98 
Lungs, location of in living, 119 
Lymphatic glands, 125 
nodules, 11, 128 
vessels, 125, 126 
Lymphoid tissue, 128 

Male genital organs, 15, 132 
Mammalian brain, 11, 73-85 
Mammals, development of, 137, 138 
Mammary glands, 137, 138 
Manikin, Suzuki, 1 (note), 139 
Manikins, list of, 139 
Material, fresh, 147, 148 
Median sagittal section of brain, 78-80 
Mediastinum, 9, 96 
Medulla oblongata, 71, 77, 84 
Medullated nerve fibers, 61 
Membranes, serous, 8, 9 
Meninges (see Dura mater, Arachnoid, 
Pia mater) 

Mesencephalon, 71, 72, 75-79, 82, 84 

Mesentery, 12, 13, 122, 124, 125 

Metacarpals, 46 

Metacarpus, 3 

Metatarsals, 48 

Metatarsus, 3 

Metencephalon, 71, 72, 77, 78, 82-84 
Methods, histological (see Histological 
technic) 

Methylene blue, staining with, 20, 21, 
34, 51, 59 


INDEX 


*55 


Microscope, compound; directions for 
use of, 17-19 

Miscellaneous equipment, 146, 147 
Mitosis, 28 
Models, list of, 139 
Motor end plates, 62 
Mounting sections on slides, 26, 27 
Mouth, 124 
floor of, 95 

Mucous membrane (or mucosa), 91, 127, 
128 

Muscle (or muscles), abdominal, 6 

anterior limb muscles, tabulation, 

53, 54, 55 
cells of, 27 

directions for dissecting, 52, 53 
facial, s 

general distribution of, 4, 5 

histology of, 50, 51 

intercostal, 6 

masses, superficial, 6, 7 

method of preparation of, 52 

mimetic, 5 

of eyeball, 89 

of larynx, 98-100 

of lower jaw, 5 

of neck, 5 

of scapula, 53, 54 

of shoulder and chest, 5, 53 

of vertebral column, 6 

posterior limb muscles, tabulation, 

56, 57, 58 
spindles, 62 

Myelencephalon, 71, 72, 77 

Nasal cavities, 91, 92 
Nasolacrimal duct, 92 
Neck, viscera of, 10, 11 
Nerve cells, 20, 59, 60 

distribution to the eye, 87, 88 
endings, 62-65 
fibers, histology of, 60-62 
medullated, 61 
non-medullated, 61, 62 
roots, cranial, 78 
spinal, 66 

tissues, histology of, 59-65 
Neural cavity, contents of, 11 
Neurones, 59, 60 
Neutrophiles, 116 


Non-medullated nerve fibers, 61 
Nose, 91, 92 

(Esophagus, 10, 12, 30, 96, 124 
Olfactory epithelium, 63 
lobes, 71, 75, 77, 78 
organ, 91, 92 
Omentum, 13, 124 
Optic chiasma, 77, 80 

thalami, 71, 72, 82, 84 
Orbit, structures of, 87, 88 
Organ of Corti, 65 
Orientation, terms of, 1, 2 
Os pubis, 47 
Ossa coxae, 46, 47 
Ossification, process of, 36, 37 
Ovarian follicle, 134, 135 
Ovaries, 8, 149 

Ovary, 131 ^ 

histology of, 134, 135 
Oviduct (see also Uterine tube), 131 
Ovum, 28, 134, 135 

Pacinian corpuscles, 62, 63 
Pancreas, 13, 125 
Papillae of tongue, 95 
Parietal peritoneum, 8, 12, 131 
pleura, 9, 96 
Patella, 3, 48 
Pectoral girdle, 3, 45 
region, 4 

Pedunculi cerebri, 77 
Pelvic cavity, boundaries of, 46 
contents of, 8, 9, 13, 14 
girdle, 3, 46, 47 

sex differences in, 47 
region, 4 

Penis, 14, 15, 132 
Peptic glands, 128 

Pericardial membranes (or pleurae), 9,10 

Pericardium, 9, 10 

Peripheral nervous system, 66-68 

Peristalsis, 126 

Peritoneum, 

parietal, 8, 12, 131 
visceral, 8, 12, 132 
Phalanges, 3, 46, 48 
Pharyngeal cavity, contents of, 11 
Pharynx, 11, 12, 86, 124 
Phonendoscope, 101, 122 


INDEX 


1 S 6 

Pia mater, 74, 76 
Pig’s foot, dissection of, 31-33 
Pineal body, 71, 72, 76, 83, 84 
Placenta, 9, 136 (note), 137 
Plan of body, 15, 16 
Plant cells, 21, 22 
Pleurae, 9, 96 
Pleural membranes, 9 
Plucks of pig, 96-101 
Pneumograph, 121 
Pons Varolii, 77, 80, 83 
Porter, circulation scheme of, in (note) 
respiration scheme of, 121 
Posterior appendage, muscles of, 56-58 
skeleton of, 3, 46-48 
Prostate gland, 15, 132 
Pubis, os, 47 

Pulmonary blood vessels, 109 
Pulse tracing demonstration of, in 
Pyloric glands, 128 
Pyramids of medulla, 77 

Radius, 3, 46 
Rectum, 12, 13, 125 

Red blood cells (see also Erythrocytes), 

113-115 

Removing brain, directions for, 74, 75 
Reproductive organs, female, 14, 131 
male, 15, 132 

Respiration scheme of Porter, 121 
Respiratory movements, measurements 
of, 119, 120 
process, 119-123 
sounds, 122 
Retina, 63, 90 
Rhombencephalon, 77, 78 
Rhomboid fossa, 84 
Ribs, 3, 40 

Roots of cranial nerves, 78 
of spinal nerves, 66 

Sacrum, 2, 41 

Sagittal section, median, through body, 
15, 16 

through brain of mammal,78-80 
through head of dogfish, 71, 72 
of mammal, 86 
Salivary glands, 16, 124, 129 
histology of, 129 
Scapula, 45 


Scientific drawings, rules for, 7, 8 
Scrotal sacs, 15, 132 
Sectioning with mocrotome, 25 
Sections, mounting on slide, 27 
spreading, 25 
staining on slide, 26 
transverse, through body, 15, 16 
through olfactory region, 91 
Seminal vesicles, 15, 132 
Sensory nerve endings, 62-65 
Serous membranes, 8, 9 
Sesamoid bone, 48 
cartilages, 32 

Sex differences in pelvic girdle, 47 
Skeletal cells, 27 

parts, superficial, 3, 4 
tissues, histology of, 34-38 
in pig’s foot, 31, 32 
Skeletons, list of, 139, 140 
Skull, 2, 42-45 
bones of, 44 
external features of, 43 
internal features of, 43, 44 
Slide collections, list of, 141-144 
Small intestine, 13, 125, 127, 128 
Spermatic cord, 15, 130 
Spermatozoa, 136 
Sphygmograph, m, 112 
Spinal cord, 11 

commissures of, 70 
gray substance of, 68, 69 
gross anatomy of, 66-68 
histology of, 68-70 
white fiber tracts of, 69-70 
ganglia, 70 
nerve roots, 70 
Spirometer, 122 
Spleen, 8, 13, 124 
Squalus acanthias, brain of, 71, 72 
Squamous epithelium, 20 
Staining sections on slide, 26, 27 

smears on coverslip, 58, 113-1 
under coverslip, 20 
Stethoscope (see Phonendoscope) 
Stomach, 8, 12, 124, 125 
histology of, 128 

Striated muscle, histology of, 50, 51 
Superficial muscle masses, 5, 6 

muscles in the living, 6, 7 * 

skeletal parts in the living, 3, 4 


INDEX 


I 57 


Suprarenal glands, 131 

Suzuki blackboard manikin, 1 (note) 

Sympathetic system, 66, 67 

Tarsus, 3, 48 
Taste buds, 63 
Teased preparations, 21 
Technic, bichloride of mercury (corro¬ 
sive sublimate), its use in 
preserving material, 52 
blood count (haematocytometer), 
116 

dissecting mammal, 8 
formalin-alcohol brain fluid, 75 
grades of alcohol, directions for 
making, 23 (note) 
haemoglobinometer, 118 
histological (see Histological 
technic) 

injection, 102-106 
obtaining blood sample, 113 
pneumograph, 121 
preparation of muscles for dis¬ 
section, 4 (note), 52 
preservation of brain, 75 
removing brain of mammal, 74, 75 
skeletonizing, 33, 52 
specific gravity of blood, 117, 118 
sphygmograph, hi, 112 
sphygmomanometer, in 
Telencephalon, 71, 75-77, 79-82 
Tendon, histology of, 35 
Tensile tissues (see Connective tissues) 
Testes, 15,132 

Testis, histology of, 135, 136 
Thoracic cavity, contents of, 9,10 
segment, 39 
vertebra, 39, 40 
viscera, 9, 10, 96-101 
Tibia, 3, 48 


Tongue, 95 
Tonsils, 86 

Trachea, 10, 12, 97, 98 
Transverse sections through body, 15, 16 
through olfactory region, 92 
Tubular type of gland, 127-130 

Ulna, 3, 46 

Umbilical cord, 137 

Unstriated muscle, histology of, 50 

Ureters, 13, 14 

Urethra, 14, 131 

Urinary organs, 9, 13, 14, 131 

Urogenital system, 131-136 

Uterine tubes (see also Oviducts), 131 

Uterus, 9, 14, 131 

gravid, 9 (note), 136, 137 

Vagina, 14, 131 
Valves of heart, 100, 101 
of veins, no 

Veins, dissection of, 106-109 
gross anatomy of, 104-106 
histology of, 109-110 
Ventricles of brain, 71, 72, 79 
Vertebrae, 2, 39, 41 
Vertebral column, 39-41 
Viscera of abdominal and pelvic cavities, 
8, 9 

of neck, 10, n 

of thoracic cavity, 9, 10, 96-101 
Visceral peritoneum, 8, 12, 131 
pleura (or pleurae), 9, 96 
Voluntary muscle, histology of, 50, 51 

White gelatinous fibers of connective 
tissue, 34 

Yellow elastic substance of connective 
tissue, 34 




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Reference And Supplementary Texts 


MORRIS. Human Anatomy 

7th Edition. A Complete, Systematic Treatise. 

By a Number of Contributors. Edited by C. M. Jackson, M.S., 
M.D., Professor and Director of the Department of Anatomy, University 
of Minnesota. With 1164 Illustrations (515 in Colors). Cloth $10.00. 


KINGSLEY. The Comparative Anatomy Of The 

Vertebrates. 2d Edition. 

“Embryology is made the basis, the various structures being traced 
from the undifferentiated egg into the adult condition. This renders it 
easy to compare the embryonic stages of the higher vertebrates with the 
adults of the lower and to recognize the resemblances and differences 
between organs.” 

By J. S. Kingsley, Professor of Zoology, University of Illinois. 406 
Illustrations. Cloth $3.25. 


DAVISON. Mammalian Anatomy 

3rd Edition. With Special Reference to the Cat. 

By Alvin Davison, Ph.D. Revised by Frank A. Stromsten, D.Sc. 
(Princeton). Glossary and 115 Illustrations. Cloth $2.25. 

FOLSOM. Entomology. 3rd Edition. 

Special Reference to Its Ecological Aspects 

A Comprehensive and Concise Account of Insects. By Justus Wat¬ 
son Folsom, Sc.D. (Harvard), Asst. Professor of Entomology, Univer¬ 
sity of Illinois. 313 Illustrations Including 5 Plates. Cloth $4.00. 


P. BLAKISTON’S SON & CO., PHILADELPHIA 





Reference And Supplementary Texts 


McMURRICH. The Development Of The Human 
Body (A Manual Of Human Embryology) 6th 
Edition. 

It incorporates results of important new contributions and forms an 
accurate statement of our present knowledge of the subject. 

By J. Playfair McMurrich, A.M., Ph.D., LL.D. Professor of 
Anatomy, University of Toronto. 290 Illustrations. Cloth, $3.25. 

PATTEN. The Early Embryology Of The Chick 

It will help the student to group the structure of the embryos, and the 
sequence and significance of the processes encountered. 

By Bradley M. Patten, Asst. Prof. Histology and Embryology, 
Western Reserve School of Medicine. 55 Illustrations. Cloth $2.25. 


HARMAN. Laboratory Outlines For Embryology 
2d Edition. 

It guides the student to a general knowledge of the processes and phe¬ 
nomena of development. 

By Mary T. Harman, Ph.D., Asst. Prof. Zoology, Kansas State 
Agricultural College. Cloth $1.00. 

WILDER. A Laboratory Manual Of Anthropometry 

It gives rules for measurements,' instruments and formulas employed, 
bibliographies, appendices, etc. 

By Harris H. Wilder, Ph.D., Prof, of Zoology, Smith College, North¬ 
ampton, Mass. 43 Illustrations. Cloth $3.00. 


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